Personally, the hype was what pushed me past the Ambivalence Tipping Point. The last time anyone really tried to get me excited about email was when Google had a mysterious beta webmail that was invite only. It was a good five years before there was anything in the market that gave me any second thought on switching away from gmail as my email browser.
That said, Mailbox is sleek but gimmicky, and I have doubts about its long-term value.
Finally getting accepted for Mailbox was exciting. I wouldn't want everyone to do the same thing, but I'm glad that they did.