EDIT: Revised after playing through it another time or two. Opinion's a good lot more positive.
I like a good challenge every now and then, but a lot of the object / enemy placement in Attaction Attack really just made it feel like there was little to no room for error. Almost all Sonic games have that sort of difficulty gap that gives you that space (minus Unleashed and Lost World maybe?), but I really don't think it really did any favors to the game itself regarding it being fun. I just found myself frustrated with how certain things were spaced just close enough to each other or just far enough away where you couldn't move through there without getting hurt or falling to your death, unless you were expected to master every specific area.
The level design itself in most areas besides that though really is nice. The second stage is one I like a lot due to the amount of downward slopes and ramps you can traverse, and the third one only triples this (that's my favorite stage by far). These are a good bit more lenient, and I feel like it's difficulty is a bit more in line with what I like I guess, though there were those couple of pits you couldn't really see coming.
The colors were sometimes a bit of a clutter, though. I find the visuals to be really stunning and probably the highest point of the game (besides general controls and game feel), but while it could be my eyes being weird sometimes, everything was so trippy with it's palette (especially for Attraction Attack) that it was a bit hard to distinguish what's what on the screen when moving on the fly, sometimes. Sure, I can get behind keeping the "CD" or "Chaotix" style visual, but if overdone it seems to be a bit noisy on the eyes. Not saying it was, though, AA just seemed to throw me through a loop.
The music is oddly also not as peppy as I was expecting.. nor varied in instrumentation. The tracks themselves have really nice composition though, and they're definitely not bad to listen to. I guess I was expecting something with slightly funkier sounds and heavier emphasis on both percussion and drums. (The title screen especially caught me off guard with that.)
Overall, its a great and solid effort. I think the visuals and controls are probably some of the best SAGE has seen. I guess with the first stage and getting repeated game overs I wasn't really enjoying it, but when I finally got past it I started to like the game a lot better. Either way though, I have full-on respect for what's come of this, and I can see its brimming with talent. Hope you'll appreciate the review, yo.