I opened a synchrony account about 5 months ago. My only complaint (and it really shouldn't be a complaint because they are protecting my money) is that the freaking security question, sign up, identity confirmation process was GIGANTIC hassle...I think they switched things up about a month ago to ease the sign up requirements though.
Other then that, haven't had any issues, just like any online bank it can take a day or two for transfers to post, but that's to be expected, customer service was fine the one time I called. I don't use it for anything but parking short term cash reserves so I don't use a ton of the features.
If you are looking to stash cash a little longer term and are a Navy Fed member, they sometimes have some good CD rates, I think right now it's 2%, last month they had a government employee special of 3% on 10k for 18 months.