So I loved playing the Bounty Hunter (too bad he got bugged, so I had to start another one from scratch >:-( ), and since the Trooper is a mirror, I figured I'd enjoy the trooper just as much. Only problem is I didn't. In fact, I hated playing as the class completely. I hated it so much that I was bored with the class by level 5! I don't know what it was about the trooper that turned me off so quickly, but it just didn't "click" with me like the BH did.
I thought Trooper was just an equivalent, not a mirror. You know how troopers get heavy weapons? BH gets pistols. Not the same playstyle therefore. I'd guess that the difference in playstyle is the reason you didn't like it.