Dear Bioware,
I've been a fan of the KOTOR and TOR games since I was a kid. I'm thrilled to say that I think this expansion does justice to the franchise. The talents need a little re-balancing (as a madness Sorc, I never EVER run out of force), but it's still fun. Progression is paced about right. Achievements are awesome. And, of course, the focused story is downright epic. Good move using more action cutscenes. In vanilla TOR, it sometimes felt like our class stories for 90% talking. RotHC balances it out and makes it interesting.
A couple of concerns I would raise, just for your future expansions. As epic as the story is, I'm concerned that each respective factions follows the same basic story. Yes, there are a couple of twists to remind you where your place is in the galaxy, but it's pretty much the same fights and enemies at the end of the day. So it's really more like one of the planetary story-arcs than an actual class mission. That's not necessarily a bad thing, but please remember that one of the most engaging things about SWTOR is that each class had a unique story. If they become too similar, it will lose that magic.
Second, the GSI missions are... cruel. Not the dailies, those are fine. The introductory missions, where you literally visit every single planet. I spent two days working on those missions. Two days. And what do I find at the very end? Oh, sorry, it's a Heroic 4. Needless to say, I was upset by this. It's very anti-climactic to work your way to that point and you don't even get to see the final prize unless you can find a few other people who pre-ordered the game and took the time to finish those quests. Heck, I still don't even know what the rewards are! Last time I ran across the galaxy, at least I got an HK-51 for it (and even though it was considered heroic at the end of that arc, I could still solo it). I still don't see the point for this GSI missions. And I guess I won't know until some peeps in my guild finally return to the game and play through the expansion and take two days to finish the quests. Just sayin'. It's a little cruel to do that.
Otherwise, though, great expansion. I'm looking forward to seeing the future content you have planned.