1. It's sheer awesomeness, that's why I keep playing it. Basically all the reasons why I chose it to begin with are why I keep playing it. The class has only exceeded my expectations, it's so much fun to play.
2. I've always liked Bounty Hunters in Star Wars lore. Not so much the characters from the movies, but the idea of Bounty Hunters themselves. Especially from a role-playing standpoint. I have a lot of fun playing as a light sided Bounty Hunter. I rolled with a Powertech because I wanted to try tanking for a change, and I liked the idea of being a beefy BH who can take a hit. Plus I love all the gadgets.
3. I haven't gotten far enough with my other classes to have a solid opinion on this one. I gotta say though I miss being able to shoot up in the air with Death from Above when I play my other characters.
4. Good question. I've never really felt like the class was missing anything, although it would be nice if us Powertechs got a 60 second CC.