First, for the bonus it does require a $200 minimum deposit and there's a $30 fee if the account is closed within 120 days from the opening date.
For the money market account, you cannot link it with another bank's checking account like you can with ING Direct or EmigrantDirect. To do ACH type of transfers would require you to open up a checking account with UFBDirect and connect it with another bank like ING Direct. But there checking accounts aren't too bad. They have small minimum requirements to avoid fees and they can be opened at the same time that the money market is opened.
As for the bank's financial stability, Bankrate.com only gives it a 2 out of 5 star rating (below industry average). Also, there are some poor customer service experiences noted at this FatWallet thread.