For me, the best part of beta testing is actually getting to find and report bugs. For instance, on the beta right now, helmets, shoulders and weapons are not functioning visually for draenei women. This is kind of weird, but that's not the point. The point is, it's happening, we're reporting it, and it's extremely unlikely it'll make it to live. A lot of people get frustrated when a beta is buggy and doesn't work, but that (in my opinion) isn't a productive attitude. You're on the beta to test it - whether it's a class mechanic that's not functioning (like, as an example, tanks actually taking negative damage in PvP
), a texture not appearing, a quest not working, what have you, it's actually kind of awesome when something goes wrong while you're playing so you can report it and improve the ultimate experience.
Of course, some bugs still get through - anyone who played the Alliance side starting quests remembers the bugs that made that very hard to play for some people. But I still enjoy finding a bug on the beta. It's like a kind of prize.