I'll just go down the line.

* The new monsters! Difficulty, behavior, how can we improve them?
Appearance wise I'm actually quite fond of the new monsters (Grave Scarabs, Glop Drops, and Dust Bunnies). As was stated in other threads I've noticed, the presence of a small-size high-volume monster adds a light difficulty to gunners, light ease to bombers, and little change to sword-users. Moreover, due to sheer volume, many undisciplined players may find themselves bewildered and unable to fight back well for that time.

Unfortunately, sheer volume alone will appear interesting for only a few moments. Afterwards the monsters, being that they only have one form of attack and have predictable positions, take on the roles of the game's punchbag monster type instead of being seen as valid enemies. Many monsters existing within Spiral Knights have at least one specific quality that makes them formidable every encounter (Lumbers have high damage to discourage clumsy players, Devilites attack fast and can strafe to avoid projectiles, Greavers tend to float around the player and can hit from just about any angle). As a result any monster that lacks the notable quality isn't seen as a good enemy but just cannon fodder or a distraction from the real thing.

That being said, cannon fodder isn't a bad idea either. If these monsters were to be mixed in with wave upon wave of other monsters and had the tendency to take hits in place of their larger comrades, their presence could potentially fire up the difficulty in many Clockworks battles.

* The new levels! Difficulty, payout, any bugs you encountered.
I am somewhat happy that the atmosphere for Danger Mission Compound 42 is planning to be used as a natural occurrence. The mix of grassfield and urban factory creates a setting in which you can properly mix many monster families together without anyone questioning its validity.

The first of my two largest concerns for this level was the scarcity of lucky boxes in general. I noted Compound levels on average had half what their clockworks counterparts carried in boxes, which when paired with the fact the crowns display is no longer in the UI, gives off a feeling that the level's payout is likely to be lower than desirable.

Second was the relative ease I found I had in being able to squeeze my way through the level. Most clockworks levels throw the player into chokepoints where he/she must fight hard and eliminate all nearby enemies or risk moderate to fatal injury. In general, the compound levels, especially the ending rooms, gave me the opportunity, as well as the inclination to completely stop fighting and just run past everything. While that may have been the intended effect, I do wish to state that it may backfire and cause players to decide to skip/avoid things on many levels, not just compound-based ones.

Little note about the last room of The Compounds, I noticed there was one setting where players can go in a circular motion, grabbing keys on the south side and carrying them to locked gates on the north. I would optionally recommend a system where going one direction, left or right, cuts it off so that players may be forced to go the other direction and face monsters on the other side instead of strongly securing one direction alone.

Another little note about that last room, I noticed during one of my Tier-1 speedthroughs that the developers found it perfectly acceptable to establish missile puppies on both left/right ends of the north hallway. While it may be out of place for me to say so, at Tier 2 to 3, it becomes notably frustrating to become under attack by a monster using lock-on attacks in circumstances where you find yourself still unable to see the monster from the beginning. Missile puppies are often regarded as tolerable because in most circumstances they are either facing away from the player (and thus passive) or have appeared on the northern side of the map and can be spotted early on. Placing them on the far left/right and having them ready to attack may in many cases lead to a few complaints.

* Thoughts about the UI?
Changes to a game's User Interface are always make-or-break decisions to the developers, and with good reason. Changes in the wrong direction can make the game less desirable to play even when they have little to no impact on the game's playability whatsoever. To this, I will split each individual detail.

-Health-
I find it interesting that damage received from monsters is no longer measured by multiples of half-pip. Adding a percentage for health is also useful, as knowing the exact percentage of your maximum health lost every time you take a hit allows you to know how many attacks you can likely withstand before finally dying. My concern about this change, however, is about viewing the party members rather than the player him/herself, as ally health is displayed by percentage rather than volume, making it difficult to evaluate a party member's defensive competence (or in other words knowing if that person is even wearing gear of a high enough grade)

-Shield-
I must say that having an indicator of physically how much abuse the shield is capable of withstanding is a convenient feature. However, like many have stated before, I do find it strange that the shield's bar often extends beyond a player's health bar. I would recommend either lengthening the health bar and simply adding splits to it for vitapods or shortening the shield bar so that its length matches up with the health bar at the time.

Additionally I would like to recommend adding a shield indicator not only for the player, but his/her party members. It is alarming how often players will fail/refuse to come to the aid of their party members simply because they were unaware that their party was in distress.

-Currency and Energy-
This feature (or rather the changes to this feature) has been discussed quite widely, so I'll make it simple.

The decision to show/hide the amount of crowns on hand is neither supported nor refused, as many other online games exercise either feature (or lack thereof). Some players desire to know how much money they have all the time, some desire to not know, and some will not care either way. As a result, I'd recommend that this feature be optional to the User (in other words, let us choose from the menu whether or not we want to see how many crowns we have at the time)

Hiding the amount of energy available would be acceptable if energy were not in regular use during gameplay. Unfortunately, players do require energy to operate elevators, open energy-based gates, operate special alchemy machines such as Moorcroft/Sanctuary, and also activate Mecha Knights and Turrets within the clockworks. As a result, most players don't just want, but need to know how much energy, both mist and crystal, they have available so they can make fast decisions on whether or not they should open a gate or continue to the next clockworks depth. Thus, I believe hiding this feature isn't an ideal call.

-Enemy Health-
The bar is useful for knowing on the fly if the weapon in use has any effect on the monster. However, like many have stated before, often a monster's health bar will appear empty when the monster simply has near 0 health remaining. To fix this, I would add a noticeable visual feature to the health bar to indicate the monster is dying/dead.

-Enemy Description (Top Right)-
It came to my attention that "detailed" information on a monster only becomes available if the player is locked onto that monster in question. The largest issue I have with this feature is that the effective range in which a monster can be locked onto varies depending on what type of weapon is being held at that moment. To my knowledge, it is difficult, if not impossible, to lock onto a monster when carrying a bomb. Lock-on range is longer using a handgun compared to using a sword. Most of all, lock-on itself can often be inaccurate and either point to nothing or the wrong monster outright. Instead of giving a large space for a small description on a targeted monster, I would recommend giving a list of small descriptions for either all monsters in the player's general vicinity or by history of attack every monster in which the player has inflicted damage upon.

Also, an issue I have with the enemy description is that while it does show the monster's family, attack damage type, and weakness, it fails to show any status effects the monster is capable of dealing. I feel that if you plan to go as far as identify a monster's weakness, you should also take the time to show what special status it may inflict on the player as well.

-Weapon Scrolling-
This is a UI feature I actually enjoy, other than the fact that the icon for the currently equipped weapon was removed. By placing icons of the next/previous weapons in line, it becomes easier to navigate to the desired weapon in the arsenal. Unfortunately, by having removed the original icon for currently equipped weapon, It has now become difficult to identify the status of, or for that matter to know which weapon is presently in use. While it may not seem like such a serious concern, I have been in a few circumstances where a player messed up horribly and explained later that he/she had no idea exactly what weapon he/she was holding at the time and panicked as a result.

-Consumable Items-
Seeing as the appearance of materials has yet to change, I find the new appearance of consumable items somewhat out of place. With the current UI, players expect consumables to have pretty much the same appearance as any other material without caring whether or not using the consumable later actually looks realistic. With this recent change in appearance, not only are the new consumables slightly more difficult to see, they seem very out of place in contrast to the rest of the game.

-Overall Regarding UI-
If there is one thing I have learned over my general experience with online games, it is that when it comes to the User Interface, there is rarely such thing as too much freedom to the user. Don't be afraid to incorporate both the old and new feature of the UI and make it selectable to the user whenever you have trouble figuring out which one is more ideal. Moreover, players may actually feel more comfortable in settings where customization is not only available but encouraged.

This ends my feedback regarding my experience with the Spiral Knights Preview Test Server. I hope that at least some portion of it may serve some use in the coming time before the official release of this new content.