Well, I didn't actually play it with anyone. But I browsed through it to see what looked good and what didn't. It's not going to be the best feedback, but here it goes:
Map Header
Well, you managed to make a ShufflarB2 map header without saying that it is a ShufflarB2 level pack. Vanilla SRB2 had issues going to the next level by itself
Knockout City Zone Act 3, UNKNOWN/10
I don't know, but there's a possibility that the Auto-Explosion may not be placed properly. I dunno. The spring that gets you through a crack on the roof...well, that crack is too small; it takes several tries to get up there. And there's nothing really on that roof. -_- IIRC, that may be the only way (as Sonic) to get to the Random Monitor, so, well, that's better than nothing. That appears (BUT I'M NOT SURE) like it would give Tails players an advantage. That's all I can say so far.
Egg Fort Zone, UNKNOWN/10
The ceiling is a little low. Kind of annoying when you hit a spring in the water and you hit this invisible roof. Because of that, the yellow springs in the water give the illusion that you can go onto the alternate path, but in actuality, you can't. You might want to look into that.
Do not make me jump for each stair on the alternate path. If you absolutely must use stairs that high, use the Ramp Sector sector type.
You have Auto-Rail. Unless you're a genius mapper, don't even try to place Automatic and Rail in the same stage. I KNOW people are going to complain about this one.
Green Lake Zone, UNKNOWN/10
Nice scenery. The stairs leading to the bases highly break up the flow because you have to hop up there. I can imagine many deadlocks resulting from this.
Techno Lazer Zone, UNKNOWN/10
What really makes this stage interesting is how the main paths are on the sides and the alternate path is in the middle. The constant stair jumping in the alternate path doesn't look like it'd be good. It slows the player down, yes, but he/she is out in the open and not in a hallway. I foreshadow that decent Rail Ring users will have a massive advantage over any Sonic player who tries to take that path.
Also, the lasers guarding the flag. It felt to me like a cheap hazard when browsing through the level. It looks cool, but you MIGHT want to alter that. Maybe. Maybe it's not as cheap as I think it is.