I finished the Black Talon flashpoint last night, took about an hour. Was bounty hunter, mercenary, a Juggernaut and myself a Sith Assassin. Only technical issue I had was that when I started the game back up in the evening the textures were completely borked, I mean no detail, looked terrible. I quit and restarted and got back the better textures. I wonder if some of the complaints are from those unlucky enough to get that the first try and not realize there is a problem. Seriously, huge difference.
As far as the Sith Assassin, I made it to level 11. So far I'm meh.. I typically play a ranged DPS or support/CC role. The assassin has a great backstab ability but by the time I get to the mob when I'm in a group they have mostly been burned down. Basically the Juggernaut leaps in with their leap ability, the DPS open up fire from range, I spend time running up to cast or melee and the mob is dead.
I'm trying to decide now if I should try out a ranged class like sniper or just stick with what I've got now that off of the start planet. Any suggestions?