Overall, I am excited to see the new installments put into the main game, but that does not mean that they are without their problems.
NEW ENEMIES:
The new swarming enemies were pretty fun to fight....for about ten minutes. Then they become predictable, and too easy to fight. I believe that all of them should have a speed buff and a tracking buff, to make them actually able to jump you and actually have a chance to maul you to pieces. Other than that, they seemed to fit well to create a challenge when paired with a group of other enemies, and with some tweaking, they can become quite fun to fight.
NEW LEVELS:
The new levels in the testing server were pretty awesome. They had cool designs, and had something that gave a good contrast to the rest of the game, so we can have a different looking level, rather than the same thing over and over again. I hope these levels, or variants of these levels are going to be put into the clockworks, it would give me enough of an incentive to go back in there!
NEW UI:
And here is where we go to the belly of the beast. When I first saw the new UI, I despised it. And now, after using it for a couple hours, I hate it even more. First problem, the shield bar. While many were excited about this new tech, i found it useless. Shields already change color, indicating the damage that has been taken to them. There is no need for a shield bar to be in the game, it just takes up space and reduces visibility. Second, you cannot see your crowns or your CE unless you open your arsenal. Now I have seen Nick's response to this, how he said, "...we've come to believe that displaying currencies on the HUD creates a very linear mindset regarding advancement within the game." The problem with this is, you need energy for pretty much EVERYTHING in the game. You cannot PLAY Spiral Knights without ENERGY. So to say what Nick said, with all due respect, is foolish. People who enjoy the game and become fans of it will make their own idea of progress. But in order to do that, they may want to see how MUCH they can play, before they start losing all their energy because they can't see their level of energy. Third, the large picture of yourself in the top left corner. What is the point? Can you not see yourself in the middle of the screen? Sure, it may be used as a menu but, once again, the same as the shield bar, it just takes up more space, and reduces the players view of the actual fights. The menu can just be put back to where it was originally, in the friends list. Finally, fourth and perhaps the worst part of the new UI, it doesn't match the art style of the game in the slightest. The old UI fit the game great, sure it wasn't perfect, but it had what you needed, your menus in convenient locations, the flat textures looking clean against the game, the buttons not taking up a huge amount of space, and a couple of gears scattered about to remind you that you are gonna go adventuring in a giant clockwork system. Now? It looks like something mashed from other generic MMOs which eventually spawned something looking like it was ripped from PSO. The new UI looks so different from the rest of the game that it feels as though the art changes to the vials was simply so the UI had something to match to. If something doesnt look like it matches with the rest of the game, then most likely, it SHOULD NOT be in the game. The old UI was fine the way it was, so, as the saying goes. DON'T FIX WHAT AIN'T BROKE!
NON-UI VISUAL EFFECTS:
There were a couple other features added that I wouldn't consider part of the new UI persay, and these features are the weapon change list and the new attack animations. I thought the weapon change list was a cool addition, though having it right in front of your face could be disorienting, and could blind you from enemies in a pinch, so if the feature is kept, believe it should be moved to another area of the screen. As for the new attack animations, I thought the new enemy ones looked pretty awesome, with a more exaggerated charge up cycle that made me feel more fearful of the attack that was incoming. For the attack animations for the spiral knights, in which an attack lands on an enemy, they look interesting, but i think they need a bit more work, as once again with the UI, it doesn't look as though it should fit with the game's art style. The next part I would like to comment on is the new elevator descending/ascending screen, and the new mission complete screen. Both of are pretty visually appealing, and unlike the UI, look as though they would fit well in the game. However, in the mission complete screen when the knights strike a pose....it looks a bit odd if you are holding a bomb.

All-in-all, I look forward to what the SK development team will do with this before it is released to the full game. I hope my feedback, and the feedback of my fellow players will help you guys make the right decisions for the game. But, please, for the love of Vog, don't make that UI happen...