I still play Custom Edition online occasionally. CE didn't have matchmaking, but more of a custom game browser. It is a fun game and it still has a pretty big population.
Also, if you are getting it for the online, instead of campaign, just download custom edition. It's free, has a bigger population, and you can mod the crap out of it. One of my best memories of that game was playing snipers on blood gulch. And all the snipers shot Scorpion shells.