Wow, when was the last time you played IA Act I? How is the experience infiltrating the terror cell on Balmorra anything like dealing with Watcher X on Nar Shaddaa? Yes the goal of 'destroy the terror network' links the two planets, but the experiences on each planet are wholly unique. In no way are you presented with the same choices, situations, anything.
It's my most recent character. And my most hated to be honest. I found Balmorra and Nar Shaddaa to be extremely similar: infiltrate terrorist cell and its backers; kill same. Of the Act I areas, I only found Alderaan to be unique. The IA story is so cliched and nonsensical, I genuinely cannot understand what people see in it.