Here's the rest of the feedback - a bit late, but there's only so much time left!
#18 (Duplex): Quite an interesting way to mash up variety with careful thinking. The use of blocks as barriers between rooms allows for rather creative tactics to collect chips around the level, and as the player progresses, the actual sense of progression can definitely be felt as the now vacant area becomes larger and allows more player movement throughout. This level also falls in that sweet spot of "not too short and not too long", at least for me. This is definitely a level I'd like to see in the final product.
#21 (Journey to the Center of the Earth): There's not too much to figure out here, but the ice maze is particularly interesting, and the overall level is beautiful. Not one of my favorites, but I enjoyed it.
#23 (Forage Whitaker): Neat take on the "think twice before picking up an item" concept. The design is very nice, too. I really want to see this in the early part of the set.
#24 (Broken Bridge Bonanza): I think this is a decent puzzle - not too easy but not overwhelming. I find it pretty interesting.
#30 (Checkered): I would like this a bit if it were smaller, but even then, this is absolutely nothing new.
#36 (Encased in Carbonite): I don't know how to describe it... but I really like this level, and I'd really like to see it in the set at some point.
#38 (Clearance): I thought I already played this in CC1, but now there's blocks?
#40 (Scarab): Interesting way to make a consistent block maneuvering puzzle compact.
#49 (The Glider Ultimatum): I quite like the lock puzzle in Vulcan from CCLP3, and I feel like this level encases that concept in a slightly different way.