In my play time thus far, I've seen some terrible framerates, absolutely abysmal audio compression, poor implementation of 3D, and dumbed down graphics. We all know that the 3DS is more than capable of running Rayman 2 at optimal settings, putting it in line with the Dreamcast, PC or PS2 versions of the game. How Rayman 3D can fall flat in any of these areas is beyond me. The only explanation is a lack of time and dedication on behalf of those that worked on the port.
Honestly, I cannot get over how horrible the audio is in this game. Sound effects simply play when they want to, and sometimes that means not at all. Rayman's punching sound effect works on its own schedule. I stood still and punched in various directions for a good 5 minutes just to try and get the sound effect to kick in. While I wasn't doing that, I was turning down my volume to do away with the horribly compressed music tracks. Seriously, the music is so bad at times that it sounds like your 3DS speakers are blown. This kind of stuff is absolutely inexcusable.
As I mentioned earlier, the 3D implementation is pretty bad as well. Out of all the 3DS games I've played thus far, I haven't had any issues with viewing 3D. I didn't get any headaches, ghosting issues or anything of the sort. With Rayman 3D, there are 3D ghosting issues all over the place. They love to crop up during cut-scenes that use fake letterboxing. In fact, the 3D was so poorly implemented in the intro cut-scenes that I wasn't sure I could play the game with 3D turned on. So far I have 3D on, but there are still ghosting issues every so often. Things get really bad when you mix 2D sprites with polygonal backgrounds, but that's another complaint in and of itself.
Rayman 2 is an absolutely fantastic game, but this port of the title is really a shame. I don't remember disliking the DS version of the game this much. I even prefer the iPhone version to this 3DS outing, minus the controls. Perhaps I need more time with the game, but as of right now I'm really upset with how little care was taken with this port. Rayman deserves far, far better.