Hello, I'm new to monks, have never played MoP, and I do get the gist of monks, but are they any good at what they do? I would guess they would be outclassed at tanking by platewearers, but I'm not completely sure, and what about other specs? Are they monks good at PvP or better just spec for healing PvE?
PS. Which would be the best spec to level with?

Thank-you in advance