I really like the way simple presents themselves. I don't think I'll join them any time soon though.
The incentive to use a 3rd party credit card is way too strong. I get things like cash back (depending on the card, up to 6% for e.g. groceries, 3% on gas, ...) and it helps building my credit score which the debit transactions on simple won't help with at all.
I do like Fee-Free ATMs, but on both of my current checking accounts (e.g. Charles Schwab) I don't have to try to find a special one that, judging from the map, usually means a 10 minute walk. I can just go to any ATM since there are quite a few banks that will reimburse costs for ANY of them.
Photo Check Deposit is pretty standard these days as well, both my local bank as well as Charles Schwab had apps that allow me to do that.
Most of the integration that simple provides (the "budgeting" part) , I probably also get with Mint. Only that Mint actually takes ALL of my accounts (Brokerage, Credit cards, ...) into account.
Besides that, the last time I checked they only accepted “Type 1 Social Security Numbers”. Sadly, as a resident alien, I only have a type 2 number (“for work”). This seemed a bit strange since pretty much every other financial institution didn't care about the specific type of SSN so far. I didn't even know there were different ones. They mention on twitter that they've "processed a few exceptions", it would probably still be very inconvenient.