I've tried it, it's pretty good. I played the first few Tribes games back in the day, and this iteration captures the fun I had with them well. The jetpack and skis are an interesting spin on the traditional FPS mechanics. Runs well clientside, and I wasn't experiencing any lag on the few servers I joined, so presumably it runs well serverside too. I didn't notice any blatant bugs or hacking while I was on, but it's still a beta, so stuff is subject to change, I suppose. I haven't tried the server software firsthand on my machine yet, too busy with college and stuff to be faffing about with more servers.