I assume that you're "used" to this UI and it works well for you but as a first time on-looker it seems very... *thinks of word* unmanageable (I'm sure there's a better word but I'll try to elaborate)
The rectangle icons - Simply, a lot of people don't use them because they often stretch the actual image (I notice that this is the case in your screenshot). It's not a very good look, which I'm sure a lot will agree with, but if you like it then that's fine!
Zero spacing on most things - The reason people put spacing between frames is so it doesn't look so busy. When I look towards the bottom of your screen it just looks like one big clusterf*ck of information which if I'm honest; it's hard to look at (Mainly referring to the zero spacing between unitframes).
Portrait - I kinda like the portrait idea but it is a bit unnecessarily large! :P Portraits are unnecessary in most cases anyway; but having a huge one is OTT.
Unitframe colours - Much better :P Didn't like the white ^_^ EDITED: As it is blue at the moment - shaman class colour, I was thinking... maybe you could have the bar colour as a very pale class colour. You could say that the current colour is just your class colour but a much paler version. Eg it could be very pale green for a hunter, pale pink for a paladin, pale purple for a warlock... you get the picture :P Just a suggestion.
Another thing I've noticed before (I cannot actually remember if I asked you about it before) is that on your buffs and debuffs you have the shaded spiral animation, a bar showing the duration of the effect, AND timer text. Just wondering why you need all 3?
All in all I can see that you might want to try something different from the MAJORITY (inb4 hate from Lyn for saying all the UIs here are the same :P) of the UIs in this thread but being different for the sake of being different is not often a good thing. Just my 2cents.