I think the site looks really cool. The only thing that is stopping me from using it is that I have to enter my banking credentials to allow it to access my banking info on its own (nightly). I may decide to sign up in the future, but I am curious as to other people's opinions on that one.
I've seen a lot of discussion around asking users for their login credentials just for their email (see this recent YC posting for example: http://news.ycombinator.com/item?id=55660), and this is obviously more extreme than that.
I got a beta invite a couple weeks ago and tried it out. It's pretty useful. Integration with the first two accounts I entered was really easy once I decided to commit and give them my credentials. I noticed later integration with another bank was much more complicated due to the security measures on the bank's site. Mint did a good job of explaining why they needed so much info and how to extract if from the bank's site.
Categorization of transactions is done really well. Most things were categorized correctly by default and I like the ui for manual categorization. You get one big overlay with every possible category visible at once.
My main complaint so far is how many times they've emailed me so far. This is aggravated by the number of places I've had to ferret out to get the emails to stop. There isn't one email pref page; you have some global email preferences and then preferences for each account that operate independently.
I've seen a lot of discussion around asking users for their login credentials just for their email (see this recent YC posting for example: http://news.ycombinator.com/item?id=55660), and this is obviously more extreme than that.