As DX said it's just some cut scenes and you get to pick which Jedi branch you want to train in (Consular, Guardian, Sentinel). I don't believe I ever paid for the droid on either of my characters (played twice through light side and once dark). Honestly I was pissed when Taris got bombed back to the stone age after all that work. Damn you Malak. Was interesting to see what happened to Taris in TOR though.
Dantooine has quite a few side quests to do (as well as picking up another companion (if you choose too)). Not quite as long as Taris (in fact most planets won't be as long as Taris (though Tatooine can feel like an eternity)) but it can take awhile if you choose to do everything the planet has to offer.