As an avid Splinter Cell fan let me just say why would anyone play the Gamecube versions? Besides the shocking controls they completely lack the feature that makes Pandora Tomorrow and Splinter Cell so amazing - the multiplayer! Not having the multiplayer mode basicly makes the Gamecube versions pointless.
These I like:
Metroid Prime 2 (not my deal, but incredibly solid nonetheless)
but haven't played them enough to know whether they really are great or just reasonable. I mean the first Metroid Prime I spent more time on and it was good but definitely not great.
This looks interesting:
Baten Kaitos: Eternal Wings and the Lost Ocean
These I don't like AT ALL:
Paper Mario the thousand year door
Just saying for me personally there haven't really been many games in the past 3, maybe 4 years on Gamecube that have interested me much. Don't get me wrong I am still glad I bought one.
Since the start of 2004 the following games have been the only ones released that interest me:
RE4 (though I am waiting for the when I have a PS2 to get that version)
Star Fox Assault
Of course there were also these games that I liked but there is not point getting the GC version when XBox versions exist:
Lego Star Wars
Alien Hominid (coming to XBLA)