The IA story is mind-boggling to me. It's one of the worst spy stories I've ever experienced. The IA, more than most Imperial citizens knows that the Sith Empire is unworthy of saving and yet, over and over again you work in their interests. I'm almost done and it does appear that you get an out in the end, but my Chiss IA would have got out of dodge after Act I and tried hard to get the Chiss Ascendency to join the Republic. I look at the IA story and compare it to movies like Skyfall. There although Bond is sorta 'betrayed', you can understand why he is OK with it and why he comes back. You can also understand why the villain in that movie is both wrong, but sympathetic.
When I got to Act III with the IA and finished Belsavis, I nearly stopped right there, but the desire to complete my legacy powers drives me on. It blows my mind that people really like:
I never post on these forums but I just had to agree with this. I found the IA story to be extremely lackluster, with a few minor high points in Act 2. Act 3's plot was ok, but it's main villain was completely lame and I found myself wondering over and over why my chiss was bothering with all of this? It was definitely a bad spy movie. Although I went through the IA story after doing the SW (epic!) and after reading time and time again on these forums how amazing and well written it was...so perhaps my expectations were too high.
As for the JC, I'm enjoying it very much. I've been in this game since launch but took a long break a few months back. I leveled 3 characters to 50 (SW, JK, and IA), when I came back I decided to start fresh and do something a bit different to my other characters so I went DS JC. I've thoroughly enjoyed the intrigue and to be honest it feels alot more jedi-ish than the JK story, not that i'm putting the knight story down, i loved it, but the JC has more to do with jedi teachings and lore.
I'm on Voss at the moment and still enjoying it, the only downside I would say is that I don't feel like my companions as a whole are as interesting as other classes I've played. If I had to guess why people bash the JC story I would say partially because people read over and over on the forums how bad it is, therefore if they play one for themselves they go into it with a bad taste. Also, it has a different pace than the others, its more about intrigue than flat out action.