Koopa Garrison Zone by Fawfulfan
I already provided feedback before, and I'm glad to see some of my concerns addressed, but there are still a few major problems. I still don't like the use of skyboxes for death pits, and some of the platforms still have really weird shapes. I also still think you're overusing cannons. There's a reason why we only use them in a single room in CEZ2. It's a perfectly fine room gimmick, but not a good gimmick for an entire stage. They also produce constant sound, which can be annoying after a while. Otherwise I still really like the stage. The lava areas are exceptional, and while it could probably stand to have more, there are tons of secrets and reason to explore the stage, which I always appreciate.
Gravity Garden Zone by EvilEnternity3000
I've seen you talking about this stage before, but actually playing it was a pleasant surprise. The gravity gimmick is very well implemented, and the visuals are quite nice, although you seem to have gone overboard with the thing flowers. The main thing that knocks this down below KGZ for me is the irritating enemy usage in a lot of places. The areas where you provided your own enemies were great, but the use of snailers and Jetty-syns just sucked. Even though you improved the visuals, I still really don't like the gameplay of the swinging chains. I also really dislike the music a lot, personally. On the positive side, your gravity ring gimmick is great and I'd love to see it expanded upon in a second act, and the room where you're jumping upside-down in a normal gravity lake was absolutely awesome. I'd love to see more of that kind of design in a second act if you ever get around to such a thing.
Cloud Convoy Zone by toaster
Man, this has problems, but overall it's really cool. Let's get the worst part out of the way first: the precision platforming near the end has to go. Because of the perspective making those jumps is incredibly frustrating, and if you fail too much you have to sit there and wait for the game to kill you. The flying turtle enemies are rage-inducing at times, and there were several deaths for me on the first blocking ship because I kept trying to jump down to the plane and ride it through the gate instead of jumping over the gate. Having the FIRST gate not allow Sonic to pass with the plane is just incredibly rude. The whole stage seems like it could use a much longer "tutorial" section where you just have simple ships with enemies before you go nuts with switches, gates, and platforming. On the other hand, the boss is wonderful, and the overall design is just really neat in general. The whole stage could just use a nice coat of polish to make it more intuitive what you need to do.
Phantom Gadget Zone by CoatRack
I'm probably going to diverge a lot from the rest of the pack here and say I legitimately liked the dark areas, where I was hunting for platforms and methods to go forwards. The slime area was also similarly neat, and the nice slow pacing of the stage was a nice break from the common "gotta go fast" mentality SRB2 has a lot of the time. The problem I have with this stage is that it has a seriously damning conflict in the design. Most of the stage wants you to take things slowly and carefully, observing everything you can before making your move. The problem comes with the things you have that force you to move or react quickly, like the claw enemies and the turrets. When you spend so much of the stage encouraging me to be careful, twitch reaction things that require me to quickly move are a really bad thing, and it just feels incredibly cheap to be nailed by a laser when I'm trying to carefully look around.
Shadow Castle Zone by Yacker and MudkipYeah!
While a lot of people have been comparing this stage for 1.X levels, I actually quite enjoyed myself going through standard platforming. The problems arised when the stage broke expectations. In particular, your use of the rotary chain launchers sucks because you hit the sky ceiling when using them, and you have invisible walls in the torch area that forces you to follow the route instead of jumping over, killing you if you attempt the jump. You also don't use the gravity reversal pads very well in some areas, requiring double reversals in one spot and being needlessly confusing in others. The whole thing could just use a lot of streamlining of the route, more alternate routes in the areas that don't have any, and less useless territory where you just have to run forward with nothing to do or look at.
Quickman by Zipper
Well, the script is really cool and the bosses are ace. The stage itself? Pure and utter rubbish. If it weren't for Prime I probably wouldn't have even bothered to try for killing the bosses at all because the stage was so unfun. While your implementation of Mega Man isn't perfect, there are several areas where your level design specifically points out all the imperfections. The worst of these is the spots where the player is likely to get knocked back onto the spikes (which isn't lethal in real Mega Man) and the area where you climb above the lasers and have to jump from a non-flat surface. You also require a few jumps that are just barely possible, which considering the quirks in your acceleration code, are a bad idea. The enemies are also downright evil. Why not include a few basic enemies that aren't projectile-firing assholes =P
Autumn Valley Zone by Root
Well, there's really not much to say about this. While the custom art isn't very good, it at least gives it a different look. The stage itself, though, has basically nothing of any interest. Your hidden alternate route is absolutely terrible, too. If you haven't mastered the basics of SRB2 design, I really suggest against getting too clever. Try making a normal, 3D stage with a basic gimmick instead of something weird like a 2D map, which many experienced designers can't get to play well.