Icancer and u is a addon specific column that will go over everything from UI's to specific addons to specific features of addons.
When you ask a WoW player what he/she looks at the most, the answer your most likey going to get in, "My screen u nub". What they really mean, is their UI- user interface. There are many addons that modify your UI, and some that are complete replacements to the standard blizzard UI. However, there is a very important problem with some of these addons. People dont know how to organize them on the screen!!!! I've seen some ui's that show raid frames multiple times, have action bars that are huge and in the way, to even having blocks of addons in their main field of vision!
A players ui is supposed to enhance game play, not make it more cumbersome. Take my ui for example. Nothing is my line of sight, my action bars are small but useable, my raid frames are large and easily readable. This is an example of a clean ui. Now i know this isnt perfect, and this is only an example of what a clean ui can be i feel that it shows my point nicely.
There is no information displayed that i dont need, and none of it overtakes anything else, it is small, but big enough that i can easily read everything that i need to. This is a raiders ui, built upon the idea that i need to know who's hurt, whats hurting them, what size heal they need etc. But paralelle to that, it is built upon the idea that i have too look at it for hours on end so it must look nice. I consider myself a minimalist, but i know and even enjoy seeing nice ui's that have a little flare. but honestly, for your sake and the sake of your party, keep it clean, keep it simple, and keep it working.