I couldn't find a pre-existing thread about this game, which is a real shame; it is awesome!
Tribes Ascend - Focus Official HD Trailer
It's a change of pace from just about every other multiplayer FPS around at the moment. Movement relies on using your jetpack and skis to navigate the hilly maps at several hundred km/h. Because it's so different to what we're used to, you'll struggle at first, both with maintaining speed and with hitting fast moving enemies. But you get the hang of it pretty quickly, at which point it becomes really fun.
Whilst it is free to play, and you can unlock everything without paying, you can speed up your ability to unlock gear by spending real money. So I wouldn't say the model is exactly perfect, but it doesn't seem to unbalance the game at all.
It won't be leaving open beta for a month or so yet, but I would definitely recomend you give it a try: