Apparently this one pales majorly in comparison to the Saturn original. Having never played a SEGA Saturn in my life (I know, I know) - I can't necessarily comment on that. What I DO KNOW though is that it would be absolutely foolish to dismiss this as a bad game, as some have.
The cut-scenes can get awfully boring, and the inability to skip most of 'em hinders my happiness greatly because the story is absolutely worthless. NiGHTS' voice is like nails on a chalkboard. It makes him/her eerie, honestly, and not necessarily in a good way.
BUT the gameplay is a blast! That's what really counts in the long run. The game can even get pretty difficult if you try and get the best grades on each mission.
For only $5 @ GameStop, I don't think you could really go wrong with picking this up. Samba De Amigo, which is an easy 10/10 (especially if played with a friend/lover/etc.) is also available used for the same price.
Do yourself a favor (yes you, reading this) and SEGAfy your Wii a bit. You won't regret it.
The last Starfox game to truly "get it right", if you ask me
*. What an awesome shooter this truly is, and it deserves every bit of infamy that surrounds it. Probably my favorite title on the N64 to be honest.
* ok, i enjoyed Starfox Adventures as well... but that's completely different