I don't really have a lot of problems with the new UI, takes some getting used to having to press i every time I want to see mist, CE and crowns and having to look at someone's eyes instead of name when I want to see their personal colour but there's one thing I truly miss.
When I look at my OWN hp the bar isn't divided into segments of 5 hp each. I'm not sure why I miss this so much, hell I could get used to it but I don't think it would be hard to change either.
Anyway it is just a suggestion so don't rage please.