When you try to place an order on Kraken it 100% of the time on the first try gives you some generic message that says something like "We're not sure if your order went through. Check back later." So you wait a bit, refresh, and it looks like it hasn't gone through, so you enter it again. You get the same message 5 times in a row. On the 6th try, your order goes through. Sometimes you end up with 2 orders going through because one you thought didn't go through just took longer than you had the patience for.
I'm being completely serious when I say this isn't something that happens occasionally; it happens every time.
They say they're working on a new engine or something that should be out in a few months, but it's a known and annoying problem for now. Other than that, I like Kraken and agree that it seems less shady than most.