I'll get straight to the point.

*The level coloring hurt my eyes. Something other than Orange would be nice. I recommend brushing up on color theory.
*I loved the new level design; the key-gate-button system was sufficiently complex to keep my puzzle-solving mind engaged (which is rare), and some of the other areas, like the multidirectional spike trap trails and statue rooms, were quite fun and ingenious. The former actually reminded me of a Legend of Zelda area; if you guys copied it, I tip my Gold Chap to you - it's great to learn from the masters.
*I was initially disappointed that the swarming enemies didn't self-replicate, but the invisible spawners will work for now. Try letting them spawn an indefinite number of enemies.
*The swarmer A.I.s were surprisingly tough to handle. I actually died to these guys! And that's a really good thing, because it means they're a challenge. They are incredibly weak to bombs though; if it's possible to make them require about two bombs to kill off (on average), I would recommend it.
*The enemies were each unique and utilized innovative A.I.s. that were reasonably balanced against each other. Well done, guys!
--That being said, they could use some tweaking. Glop Drops can't be safely comboed, ever. They are the most dangerous swarmers, followed by the Dust Bunnies that will murder you if you are too lazy to kill them, and then the grave scarabs, that can fly from a long ways away, but can't track you. They are not *completely* balanced against each other, but it's good enough as-is that I won't complain too loudly if you leave them alone.