There are fights in CO like the event bosses, where if you do not block, you die. Some where if you did not buy a block power and rank it up, you will die.
There are a lot of things I do like about CO like the power armor set, some of the travel powers like swinging and a lot of the character creation options like material for each costume bit (cloth, leather and metal), accessories for the upper arm and thigh. Auras that only cover your clothing.
Here is some examples.