The queueing system could use a ton of work. Because of the huge imbalance between alliance and horde populations, I find, when I try to join up with my alliance characters, the wait can sometimes be very long. It's not bad for my horde character, though.
When I do manage to get in, it's some of the coolest PvP I've ever experienced. The CTF BG is especially fun. It kind of reminds me of Nox's CTF, at times, though it's much more difficult to capture a flag without the help of your teammates. Alterac is pretty cool, as well. There's a ton of things to do that can help your raid. You can rescue your air marshals to start an air raid, you can take over a mine to upgrade your side's NPC's faster (which makes destoying towers, etc. more difficult), you can round up the rams that escaped from your stables to start a cavalry charge, you can turn in armor scraps to provide materials that would upgrade your NPC's and do a lot of numerous tasks on the side. There are even raid bosses that will pop up towards the middle of the map for a quest with good rewards.
That's in addition to the pure fighting you can do, which can be quite fun when you have towers to hide in, etc. The only problem I have is when the fighting is concentrated around graveyards. That can sometimes be annoying. But, overall, it's a cool experience.
There is also a lot of good rewards to get from Alterac as you raise your reputation with the faction that represents your side--for Alliance, that would be the Stormpike Dwarves. You can do various repeatable quests--such as turning in parts of the trolls, orcs, etc. that you kill--to gain faction with them. The rewards look like
this.