Quote from TianZi
I played my DH to paragon 100, and DO NOT recommend it for anything relating to mid-MP farming. While I was able to do MP10 and solo Ubers on it, pretty much anything past MP2-3 already felt inefficient compared to playing my monk. Basically it's slow, but does work.
If you're fine with low-MP farming, than I would say DH is a good place to go. I was able to keep up fairly consistent 90-100m exp/hour while paragon leveling my DH.
I love my DH, but he falls behind other classes once you get past MP 2 or 3 :0(