You can't consider yourself a true FPS fan if you don't like this game.
The mecahnics of the Tribes series are unrivaled in the multiplayer FPS arena. Nowhere else have jetpacks, turrets and inventory stations provided such a perfect mix of action and strategy in a game to date. The commander view was revolutionary, and even games like Battlefield 2 that advertise a strategic ""commander mode" as a major game element don't come close to the flexibility and full-featuredness of the Tribes 2 commander map.
With unique modes like "Rabbit" and "Hunters" in addition to a slew of other multiplayer modes, Tribes 2 has more replayability than any other FPS of it's kind (except UT2004, but there are just so many modders who love that game).
Before you can say that you're a true FPS player, or even any bit of a hardcore gamer, you've got to have a serious appreciation for Tribes 2, because it is indeed a timeless classic.