It's disruptive all right; it fucking keeps bothering me about trying it right after i sign in to gmail. And it doesn't seem to take 'no' for an answer.
I mean, they opted-in how many millions of people? It isn't surprising that some percentage want it off, or that they consider gmail a tool for JUST email, or they don't want all that in the way.
I personally was wary of it, but I really do like how easy the implementation is, and already see comparable traffic in Buzz to what I do on my Facebook -- only I have less clicks to get to it.