i beat it last night. main game holds up so well. it's still my favorite 3d platformer from that era. fps stuff has never been a big deal to me- i can't tell the difference between 30 and 60, but this would go from smooth to not-smooth somewhat occasionally. it wasn't a big deal to me. the ghosting during the cutscenes was annoying too, but again, not a big deal.
the load and saving times are way too fucking long though. those bugged me a great deal. especially if i jumped into the wrong level and had to back out again.
aside from that, the game was a lot easier. in the original, rayman kept damage when he blew up or 'died' and this time, health replenished every time. the controls felt like they'd been tweaked too. while swimming was a pain (again, only played the n64 version over 11 years ago, so i don't have too much to go off here), a lot of segments like the bullet/bomb riding/flying things were easier to go through. i'm not sure if that was the slide pad being superior to the n64 analog stick, or the 3d helping me along, ubisoft tweaking the controls for those segments, or just me having better reflexes than i did when i was 14, but i managed to pretty much breeze through them when they gave me tons of trouble the first time around.
i said it earlier, but the music is incredible. and i didn't know the music was that incredible because i only played the n64 version.
anyway, there were a couple of reasons i got rayman: i hadn't played it in 11 years and i wanted to see how it held up; i figured a 3d platformer would be the best demonstration of the 3d effect (s'alright, but the sprites make it very obvious this is a game from 1999); i was kind of on a michel ancel kick after beyond good & evil hd; and i figured a 3d platformer would have the best use of the slide pad (i played sm64 ds on sunday and it's still barely playable as ever, but rayman 3d works really well).
so yeah. it's pretty fucking bad that it's not a polished version of a game that's over a decade old, but ubisoft doesn't really care about its michel ancel games so that's about par for the course. there's still a good game there if you're willing to put up with the load times and don't have an issue with framerate hiccups.