It's not awful but I, personally, am staying in T2. I worry that the mandatory requirement to have 3 different color schemes is making life difficult for their art team--and for their players. I'm in favor in theory of heroic gear looking better than normal; but often the heroic set is the only one that looks decent at all.
Also, black and red are rogues colors. Can't they just accept it? Could probably live with a touch of warlock green and fluorescent blue. But definitely black.
I really like the aesthetics of HM T15. It's a mix of Predator and Assassin's Creed. Once I get the full set, I will definitely be mogging (not mogging?) to it. Well, unless of course, my server's Black Market AH decides to spit out the last 4 pieces of Bonescythe that I need.