I replayed Goldeneye the other night, then played the new one for Wii shortly after, and I found myself so bored I had to hit the bong to keep myself going, and the only thing that kept me going was laughing at how terrible everything in the game was.
Some missions in Goldeneye for N64 were a mere 4 or 5 minutes, but I was so drawn in by the game that they felt like hours.
On the other hand, Goldeneye for Wii, a mission is a good 30 mins running through it like an idiot, and you just want it to end right from the beginning.
Also, WTF, where is Sean Bean...
EDIT: Wow was so depressed about Sean Bean being absent from the game I missed my point.
If you can keep the game good, it can be 5 mins long or 500 hours long, and never get old.