I've recently started using nUI, and now nUI+ as well, and the only problems I've run into are that after I've been playing for a while, the ESC key will not pop up the Game Menu - it will still close windows, etc... Just wont open the menu. This is fixed each time with a /nui rl. I have not yet started testing to see if this is a conflict with any of the other addons I've installed recently - I will try to get to that on Monday.
I was also going to add that my player/target (de)buffs weren't showing without using the nUI_AuraButtons addon... Except that when I went to try and take a screenshot of this behavior - all of a sudden it was working correctly.