Okay, so I spent like one entire hour typing out a review post. Then the login system decided to be an asshole and went all 'bluh bluh you need to log in' while I already was, and I lost my entire post in the process.
So, I decided to only post my ratings, to give an impression on how much I like each map, and I'll probably add comments later.
GFZ1 - 2/10
GFZ2 - 6/10
GFZ3 - 1/10
THZ1 - 2/10
THZ2 - 6/10
THZ3 - 5/10
DSZ1 - 9/10
DSZ2 - 8/10
DSZ3 - 6/10
CEZ1 - 3/10
CEZ2 - 3/10
ACZ1 - 8/10
RVZ1 - 5/10
ERZ1 - 9/10
ERZ2 - 10/10
ERZ3 - 8/10
NAGZ - 9/10
Lime Forest - 4/10
The outside area is quite good. Maybe a little small, but it's not hard to navigate and it looks nice. The other parts, on the other hand, are ugly and cramped. I mean, it's wood, wood and more wood, and it's a bit hard to navigate in the bases. They also seem to be camper heaven. However, the items seem to be properly balanced for such a small stage, and it isn't too bad of a stage.
Cloud Palace - 3/10
Okay, Cloud Palace is decently sized at least, but the path balance is extremely off. The upper paths have two WRMs and both Grenade Panels, and it's too easy to just run to the other side. The middle paths are too hard to stay on with heavy lag, and it only has the Bounce Panels (and all the ammo for it). The lower path has both Explosion Panels, the SRM, and it provides the easiest way to get from base to base, seeing as it is just a straight line. The hell? The visuals are rather bland, but there's not a whole lot you can do with the aerial ruins theme. Lastly, the remaining two WRMs and the Rail, Automatic and Bounce Panels are too far away from the main action, so they rarely get used.
Silver Cascade - 2/10
This level, in contrast to Lime Forest, is too huge. It takes an eternity to get to the other side, especially when you have to take the underwater path. Said path also has the most massive chokepoint in all of SRB2: someone can just wait there, and bomb you to death/drowning before you have the chance to even defend yourself. Unfair much? Most weapon panels are too close to each other, just like the WRMs and the SRM, and the ammo seems to be quite absent, aside from the clumps of them at both sides and near the weapons themselves. The bases also seem to be camped a lot, and the graphics are very dull because it's grey all over, which makes it look depressing and ugly.
Icicle Falls - 8/10
Almost a polar opposite of the previous stage because it's really small, but this stage doesn't try to give you the standard CTF gameplay. Instead, Icicle Falls enforces a more quick and frenzy playing style, which is a nice change of pace compared to the other stages, and that makes it better than the other CTF stages. The powerful items are placed properly, not too close and not too far from each other, and the visuals are superior over all other stages' visuals in this division. Nothing else to say, really, aside from the fact that the bases might be too indefensible.
Twisted Terminal - 5/10
This stage is the epitome of average. However, that still makes it better than most CTF stages in the official rotation. For instance, the weapons are properly placed, the ammo not quite. The visuals are average, nice textures and details, but little variation between them and said detail is improperly balanced around the stage. The layout is good, the lack of paths isn't. The gimmick is fun, the bases being easy to camp in/around isn't. In the end, everything balances out to a perfectly average stage.
Nimbus Ruins - 7/10
Like Icicle Falls, the different playing style of this stage makes it better than most stages. Nimbus Ruins forces the complete opposite: instead of quick and hectic, it requires you to take your time, or else you die. The high death count obviously can't be appreciated by everyone, but I like the contrast it provides, and it makes it all the more satisfying when you actually capture the flag. The bases are not easy to camp, and the items are balanced. Only flaws are the extremely boring visuals, and how the stage can become unplayable with heavy lag.
Jade Valley - 7/10
I just can't understand why this stage wasn't in 1.09.4, it would've been an absolutely great stage there. This is one of the few classic levels that works great in 2.0, the only obvious leftovers from the original are the visuals, they look rather ugly in comparison to most other stages in this division. The layout is good, the items are balanced, and there just aren't any major flaws.
Noxious Factory - 6/10
Another port from the classics that works in 2.0. The outside is good enough, like the indoor areas. However, they both look a little boring, even after the changes to the outside that were added in 2.0.5. The weapons are decently balanced, like the ammo, but some of the WRMs might be a little too close to each other. This could be a result of the stage being rather small, but it isn't too big of an issue. The slime might be a bit annoying under heavy lag, much like the SRM path, but in the end it all balances out to a decent stage.
Tidal Palace - 9/10
Wow. This stage left me speechless the first time I saw it, it just looked that great. The textures are awesome, and there's a lot of variation between them, which makes the level look beautiful. However, I quickly noticed this stage didn't only have great looks, it also had a great layout. Unlike others, I don't think it's too big, especially considering how everything is rather connected to each other. The items are greatly balanced, you have to go a bit out of your way to find them, but not too far. But the absolute best thing in this stage has to be the gimmick. The rising water gimmick has to be the best gimmick I have ever seen in a multiplayer stage, it greatly succeeds at changing the gameplay completely every 45 seconds. The only flaw I can find in this level is that some parts might be a bit on the cramped side. But other than that, this stage is perfect.
Thunder Citadel - 7/10
Another nice looking stage, and again with a great layout. However, this stage is a bit too large, and it doesn't really have an original gimmick to go with it. The items are properly balanced, and the outside area looks great, despite the low texture variation. The inside area looks a bit more boring, but still quite nice, seeing as it's hard to decorate castles properly. A nice stage, nothing really special.
Desolate Twilight - 3/10
Wait, where did this stage come from? This is a great quality drop compared to the other stages, because it's so dull and boring. The layout is extremely flat and open with just a few really high areas, the visuals could've been decent were it not for the extreme darkness which makes everything look depressing, and the powerful items are just too easy to get to. I would have said more things about this stage, but there's barely anything else left to talk about, so...
Infernal Cavern - 7/10
...I'll just go back to the fun stages. This stage, like some others, enforces a different playing style. Infernal Cavern requires you to be more careful, if you don't want to end up losing 50 points per death, because of the high amount of lava and flamethrowers. The layout might be a bit cramped, but this is not as big of an issue compared to other stages because you have to move rather carefully in here. The items are, like most other stages, nicely balanced, although you might want to change the deafult item of the SRM. The visuals are also really nice, unlike most other fire/lava based stages.
Frost Columns - 8/10
Another great stage, with a great layout and great item placement. The ice gimmick makes for frenzy fighting, while you can also go a bit out of your way to collect some more powerful items, and quickly resume to the action when you've done that. In other words, the layout is great. The visuals are not quite up to par with everything else though. I mean, there's a lot more you can do with the ice textures, and I would expect the developers to do exactly that.
Sapphire Falls - 6/10
While it is comparable to Noxious Factory in terms of quality, Sapphire Falls is quite a different stage. It's open and large, and it has no hazards. However, both stages have decent, maybe a bit unvaried visuals, and decent item placement. This stage is also a classic stage that works well in 2.0. However, the inescapable river is annoying under heavy lag, and the lake might need some more interesting things, both item- and detail-wise. No real problems otherwise.
Meadow Match - 10/10 1/10
omigosh dis stage is a klassic and it is soooooo much fun i mean it looks great the items are not to easy to get and not to close to each other the stage totally isnt a sonicthokfest the stage totally isnt to simple and to flat and it is just overly awesum and stuff and dis stage is just perfect in every way thank you stjr for porting dis i luv u so much for doing dat!1!!!1one!11!!!eleven!11!