I've been happy with the Trooper so far. I intentionally only played Empire during beta so as to not ruin the story for Launch. Having now experienced the opening chapters for the Inquisitor, Agent, Bounty Hunter, and Trooper, I have to say the Agent's was my favorite so far (a very nuanced story) and look forward to experiencing the rest down the road when I'm ready for an alt.
The Trooper was happily not far behind in quality (though, the first twist, was a little predictable) as compared to the Bounty Hunter's early twist. The BH was a lot more unexpected, turning your "get quest, do quest, turn in quest" expectations on its ear just as you get into the familiar rhythm.
I am very glad about this because I was really disappointed with the linearity and predictability of the Inquisitor's story. The Inquisitor was the first one I experienced and as a result I was worried BioWare's dramatic flair was going to be reduced to simple linear plot points to make it fit the MMO mold.