EDIT: ooh -4, I guess ya'll REALLY didn't want to be warned. It was just intended as a friendly warning but in reality I don't care what you do, go ahead use Mint all you want then.
A few years ago several credit card companies removed running totals from their online transaction histories, more recently they removed them from monthly statements also. It turns out that without a running balance customers are more confused about what is going on with their accounts and spend more money and don't notice certain fees. Running balances have been standard for decades and then the banks figured out they could screw people over by removing them.
When I noticed that Mint does not do running balances even though it is one of their most requested features [1] I knew who their loyalty lies with, they've proven that they'll make the user experience worse in order to please the banks. If Mint is not going to help me understand my money better then what's the point?
[1] http://satisfaction.mint.com/mint/topics/please_add_a_runnin... (Also fishy, notice that this request with 193 likes doesn't appear in the list of popular ideas http://satisfaction.mint.com/mint/ideas/popular)
That said, I like the idea of mint in general. It's depressing that banks can't (won't) figure out read-only credentials for use cases like this.