DK/Pally are a pain in the ***, but it's not impossible to beat them. Most DK/pally's are amateurs. By amateurs I mean that they will have holes in the way they play, and if you take advantage of those "holes" you can beat them. Plus it's VERY satisfying to beat an overpowered class, especially if they happen to be good.
I honestly find a lot more frustrating to lose against a balanced class/combo. They beat me fair and square, I have no excuse for losing except for being the worse player. It hurts your ego a lot more than "Oh they beat us cause they're OP, big deal". It kind of depends on how you react to losing or winning or just playing against op classes in general.
Watching this video
http://warcraftmovies.com/movieview.php?id=119787 just reminded of how much fun I CAN have in WoW despite all the negativity around it.
@matiasdk You're right the game isn't completely at fault for ruining my life, it just hurt my highschool life =P. But it was my fault for letting it do so, I was young so I wasn't as capable as I am now of controlling how I spend my time. Which is why I'm going back and figuring out whether or not playing WoW is safe now.
And I'm just asking for opinions btw... Well I'm getting what I asked for so I'm pretty happy with your comment.