The classics with a new coat of paint.
Reviving the classic is, in my opinion, a very good thing to have done.
In the original Pokemon games, you were stuck with playing a boy and your only choice was to give him a name. In Fire Red, you now have the choice to play either a boy or a girl. I chose the girl because the boy was basic, so why not play the girl this time?
Also note that each gym leader now looks like their counterpart from the Pokemon cartoons. You can also catch other Pokemon from Ruby and Sapphire (and I think Gold and Silver), but I'm not too fond of the newer Pokemon; they're not very convincing and a lot of them look too robotic. Oh, and their names are stupid, too. (Pineco? Ledyba!? C'mon...)
Another great thing that was added was the "vs. seeker," and item which lets
you earn a rematch from trainers you've already fought. This wasn't available in the original games. In order to level up your Pokemon in the original games after defeating every trainer, you'd have to challenge the Elite Four over and over again. (geez...)
The game still keeps the classic music for each town, battle and so forth, adding new ways to play, and...other stuff that I can't remember right now.
I don't care what others may say, this game, along with the original games, are the best! Diamond and Pearl may have loads of new features and the ability to catch even the old Pokemon, but the original 150 Pokemon were the ones who brought this series to the top. Go classics!!