I think there is more to him than we even know. Most underrated Hokage, though get's a lot of hype lately for no reason (Creator of Edo Tensei for example, has Space/Time Ninjutsu too).
Presumably he was way skilled in Suiton than Kisame, and that's an awesome feat already.
Do you think we should get more Tobirama flashbacks and details about him? He also has Senju's DNA for the hell's sake since he is one of them, Hashirama is not the only one with it.