touchwiz, in and of itself as just a oem skin like blur or sense, isnt THAT awful imo. the problem is that samsung has made it like a parasite that has its claws in every aspect of the system.
for example. *most* android phones just have a framework-res that controls all themed aspects of the phone. samsung has framework-res AND twframework-res which is a headache.
tw cant be killed easily either.. it controls literally everything....on a sense phone for example you can install adw...freeze/delete sense with little to no issue....here you can *replace* tw but you loose sync functionality...and you cant straight delete it like another skin.
a great deal of the issues the devs have (amongst crappy code) is that tw is a virus that fights for its survival and will take functionality with it when you want it gone.