Just got back from the netgame, here's my reviews of the levels:
MAP01 - Hidden Palace Zone
This level was pretty good compared to the others, but the walkways that connect the 4 outer islands are kind of thin, making it easy for players to fall off. The combination of special rings was good, but I would have liked to have seen more places to hide behind, as Rail-Explosion is a rather powerful combo in flat areas. I give this map a 6/10.
MAP02 - Splash Fight Zone
I found this level to be too bland, there was no change in the landscape, it was all flat. There were WAY too many rail rings in the level, and there was at least 1 of every other special ring in the level as well, which gets a little overpowered when someone manages to get all of them. There really wasn't a whole lot to do in this level. I also noticed that the level was missing Deathmatch Player Starts, so everyone always spawned in the same spot every time. It was a little fun to be floating in the air shooting at each other though, so it earns a few points for that. I give this level a 3/10.
MAP03 - Tails Base
The first thing I noticed about this map is that there were no single rings, as well as no weapon rings. There were a few silver ring boxes as well as a ton of shields, but being that all of these are inside of the base part of the level, there was no reason to go look at the rest of the level, which looked quite well I might add. This level could actually be pretty good if there were more rings, but for what I've seen I'm going to have to give it a 5/10.
MAP04 - House of Chaos Zone
There were many missing textures, but I'm not really sure if that's what they were trying to do or not, considering this is supposed to be a House of Chaos. Again, having all of the special rings in one level can be really overpowering when one person manages to get all of them. This level also has no Deathmatch Player Spawns. I personally found the level to be a bit fun though so I give it a 4/10
MAP05 - Subterranean Sickness Zone
This level looked very nice when it loaded, but with the good looks came a drop in framerate. All of the light blocks made the game slow down a bit. If you were to fall in the lava, you'd be dead since there's no way to get out, but if you can't manage to get away from your dropped rings to die, you'll eventually have to wait until you drown. The level was pretty fun, though. I give the level a 6/10.
MAP06 - Triad Trials Zone
This level was pretty good. A nice combination in weapon rings, as well as a good layout. The level was a bit too large, though. I found it rather hard to find my opponents. It was also a little difficult to run on the ice in the sky part of the level. I give this level a 7.5/10.
Suggestions:
MAP01 - Make the walkways a bit wider, and maybe add a few walls
MAP02 - Try to stick to 3 Weapon Rings at most, one of them being Infinity. Remove all of those Rail Rings around the edges. Add Deathmatch Player Spawns. Make a few walls, so it's not just a big open area.
MAP03 - Definitely add more rings, and add more of an incentive to go to the other parts of the level, instead of staying inside of the base.
MAP04 - Fix the missing textures (unless they were intentional). Stick with only 3 weapon rings, infinity being one of them. Remove some of the automatics, there's too many in my opinion.
MAP05 - Remove some of the light blocks, playability is more important than looks. Make it a little easier for Sonic to get around the level. Make the ground below the lava a bit higher, so that you can get back out of it.
MAP06 - Maybe make it a little smaller, so that it would be easier to find others. Also, make the ice a little bit less slippery.