The only thing I dislike about Transmog is now I have to check every item just in case it looks cool, I can't just blindly sell everything. The alts I'm currently leveling, all their bags are full of junk items that I don't have the will to get rid of. It was bad enough before with my hoarding everything now I have more to look out for
In all seriousness I love it. Best thing about it just being about to wear something else if the current item isn't to your liking. Before I think I would have just taken the reduced stats.
I remember wearing this helm all through tBC zones.
http://us.battle.net/wow/en/item/63672 One of the best features they've ever added.