I have to say, I really enjoyed the way the sprites' skill mechanics work overall. I wish there was a temporary mission that would let us take maxed sprites out for a test drive to get a better idea of the full picture of each sprite's skills, but here are some thoughts on what we see in the missions:

Drakon: I was surprised how much I liked Drakon--I'm not generally a DPS person, but I enjoyed the way firebolt and flame barrier complemented each other. One thing, however, that has already been mentioned elsewhere: the cooldown after using a sprite skill (especially the more advanced skill) feels crazy long. I would really recommend either slightly shortening the cooldowns, or separating the cooldowns for each sprite skill. I feel like a lot of the potential for sprites lies in being able to combine their skills--turn on flame barrier before activating a party pad, launch a firebolt at the baddies as you charge in with your flame barrier up, etc.--but of course we can't do that right now.

Seraphynx: The initial writeup on sprite skills left me with the impression that ray of light was going to be more defensive (i.e., send up a ray of light while kiting to slow down the baddies chasing you, give yourself and your team some time to breathe--more of a barrier than a straight up belt to the face), but it felt much more offensive. I will have to test again, but it seemed like it had a bit of knockback in addition to the damage? This also brings up the second big point that has been mentioned elsewhere: it is relatively difficult to aim sprites' attack skills. Not only do we have to guess at the skill's range, but by the time the brief animation has completed there is a good chance that the baddies are no longer there, as they are still aggroing to the player's position after the skill was initiated. Also, the heart attack skill doesn't seem to be dropping any heart at the moment, but even if it was I wanted to add that based on the small graphical change to the targets marked by heart attack, the starting duration of the skill seems a bit too short. With gear appropriate for the mission's level, I was lucky if i could kill a single baddie before the attack ran out.

Maskeraith: Out of all of the skills that we got to test in the sprite missions, caustic quills was my favorite by far. Minus the range-finding problem mentioned above, it felt very natural to use: by the time the quills had marked a target, you had plenty of time to be in the baddie's face to set the quills off. Shadow cloak also worked well, though I think a slight graphic tweak to make it more clear that the skill has been activated would help.

Other sprite mission feedback: The lore is fun, the first level of each sprite mission was fun, but the second level of each felt a bit ordinary after the extra bells and whistles of the first level--minus the new battlepod animation at the end of the second level of Drakon's mission. I just wish the second levels had a bit more character. Also, The Collector was AWESOME. I loved the look, I loved the variety of attack patterns, everything. The only minor note I would add is simply that I want to know MORE--it feels a little odd that gremlins have constructed this scary-looking critter to round up sprites for some unknown nefarious purpose, but we don't get a little more flavor text about The Collector after beating it.

Sprite leveling and skill points: Leveling feels way WAY too grindy. There might be a small glitch in heating them (maybe?): it seemed like there was a cap on the amount of heat they could gain per floor, so even if they were low-level there was no way to get a complete level of heat without running 5-6 floors. You can see this running through the fast advancement mission. Also, there was something about the combination of managing a sprite's appetite with both heating and having to craft items that felt extra cumbersome--and that's not to mention the actual amount of resources necessary to get a sprite up to a high level. Also also, and this is a minor point, but the name 'skill points' seems like a bit of a misnomer given that we only need three 'points' to max a skill's augment. I think when most people think of 'skill points' they assume you're going to be accumulating a lot of them, but based on the relative rarity of hitting one while leveling, something like 'skill token' might make a little more sense--corresponds with the relative drop rate of other tokens from treasure boxes. Lastly, it feels a little strange to have a sprite be 'fully grown' by level 50. By the mid-60s when I finally ran out of crimsonite I had two of three skills totally maxed out, and one of three of the remaining augments maxed. I would guess that I could have had my Drakon's skills totally maxed by around level 75 (since I only needed another 6 points to be totally maxed out on everything). I guess my point is: I'm not really sure why I would keep actively grinding past level 50, let alone level 75 to have everything maxed out (other than for completion's sake). And if there was some kind of cap that prevented you from choosing your ultimate before your sprite was level 100 or something, I doubt I would push through based on the amount of resources needed to take it as far as I did.

I will add to this after additional testing runs.