Working under the assumption that Marc Hedlund's post - on why Wesabe didn't make it as a personal financial aggregator - is accurate, there are a couple of superficial conclusions: At play in success are convenience, utility and perceived utility - which is not the same thing as actual utility.
By Hedlunds reasoning, Mint was way better at perceived utility than actual utility, having a low quality of imported financial data, but was clearly more convenient.
Supposing only these three things are in play, there are two possible conclusions: Utility doesn't matter, only perceived utility does. And the other one: Convenience is essential. You don't need to compete on utility above a basic threshold, you need to change the rules a little, so people care about your product at all, and then you simply win on convenience after that.