This came out a couple weeks ago. No one here has mentioned it, so I thought I would post a few comments about it, since I got it a few days ago.
Tron for the PC was a good but not major success FPS with a few mini games, like speed bike racing, thrown in. It captured the look and feel of the original movie very well, and a updated version is coming out for the XBox next month.
Tron 2.0 for the GBA is a spin off -- you can play either Tron or Mercury through a number of stages, trying to protect the ENRON computer from a mysterious hacker. It's a standard platform game but has some fun elements to it. Voice is used in the game, three save files, and you can play tank, speeder, and flying games (and also play them as mini games).
You can also play said mini games with friends if you link up to them.
But ALSO included with the game are ports of two arcade games that have NEVER gotten a home release -- Tron from 1982 and Discs of Tron from 1983, both by Midway.
The ports are dead on. My only small gripe with Tron is that to move your arm you use the L and R buttons -- not the best choices, as it can make some of the stages hard. But you can continue from where you left off by just dropping a 'quarter' when you hit start.
I never played Discs of Tron in the arcades, but comparing it to MAME I don't see any differences here either.
I love Tron in the arcades, and this saved me the desire of buying a machine someday.