The N64 is a great console and can be picked up very cheap these days.
Nintendo make great games and the N64 has loads of them.
The fact that the N64 is a cartridge based console means there are no loading times.
The official controller is probably the best ever designed and I cant think of any other console pads that have a joystick, dpad, 6 buttons and a trigger on them.Its also very comfy to play too.
But the best thing about the N64 for me is the multi player games. The N64 has 4 controller sockets so theres no need for a multi tap. There are some really amazing games for the N64 and most go for reasonable prices on ebay.
Here are some recommended N64 games:
Goldeneye (and Perfect Dark)
Mario Kart 64
F- Zero X
Diddy Kong Racing
any of the Mario Party games
The N64 also has some great single player games to look out for:
Super Mario 64
Zelda Ocarina of Time
And if you don't mind paying over £20 for a retro game - go for: Conkers Bad Fur Day - one of the funniest games you will ever play and the multi player is also very very good.