It has its ups and downs, but it's still fairly active as far as general play goes, and if you're into the competitive side of things, you shouldn't have too much trouble getting into the game. The only real question of activity is really on the developers' side of things. Every time I check the official forums or play the game it seems like there is still plenty of player interest in the game, but the last few updates have been underwhelming and content additions have been pretty scarce, so there has been a bit of concern that Hi-Rez is focusing on their other projects and pretty much letting Tribes fade into the background. However, it could go either way, and the game is still plenty of fun as is.
If you live on the east coast, yes. West coast, no. --- Dear Diary, today I was pompous and my sister was crazy. Today, we were kidnapped by hill folk never to be seen again. It was the best day ever. - Jayne