I love kisame too, even though some people keep ragging me for it lol.

His drawbacks are:
1) lowish def, so susceptible to R1 nuking if opponent is aligned directly (worst case lightning blitz team) since team heals arent up and running yet (for water main teams)
2) Control if water main and dont have RoW

Dont underestimate how annoying the 20 chakra absorption is against teams that are reliant on counterplay/interrupt or specific chakra per round count like tenten/mabui/mei. Leading R2 with kisame is great as well, it forces your opponent to prequeue his mystery leaving him open to being disrupted.