For a machine as incapable as the DS the emulators are awesome.
It is as said before, most GBA games run properly but the SNES is just being bottlenecked by sounds channels or something like that, correct me if I'm wrong.
If the SNES game you want to play has a GBA re-release, playing the GBA version is recommended as a general consensus.
For the DS it doesn't get any better than this though and the chances of getting any better emulation is minimal, unless they will get picked up by someone else, who will try and improve them further, but the latest author of the emulators has kind of said these are the final releases, except for maybe some minor bugs, that could fixed easily.
It is all a matter of perspective, do you just want to play games or do you want picture perfect emulation, if the latter is the case you might just want to use pc emulators, since you can't expect hardware like the DS to get great emulation. it is great considering the DS's limitations though.
