Pretty good...
First of all, rearranging abilities is a real pain, since you have to remove everything and reallocate every time you want to change the move order. Why can't you click and drag them around on the bar?
Secondly, there is no "queue". You can't click an ability while another is being used, so you're forced to frantically click on the next move you want to use.
Now my hand's been in horrible pain for the last 9 hours.