The benifits of being in moonkin form are 4% spell dam from master shapeshifter, +10% int from furor, +370% armor from items, single target crits have a chance to regen 2% total mana, and 15% of spirit adds to your spell power. Also immune to polymorph. I currently run 1 tree, 1 moonkin, and 2 balance not speced for moonkin form. I'm only 65 now so I may change.