I played the SWTOR beta all day Saturday. Given that the confidentiality clause has been lifted with this latest beta weekend, I figured I'd share my impressions regarding the story/conversation system because maybe writing them down might help me to decide whether I'll buy the game myself.
Chiefly, I'm impressed - this game definitely does a terrific job of tying KOTOR-style decision-making and story-telling into an MMO, which remains one of Bioware's primary selling points. Even when in a group, you can make decisions that alter the outcome of the mission or quest. Most of these outcomes are contained within the immediate conversation, but nevertheless they do much to make the player feel like a unique character in the game world rather than just another hero destined to slay 30 womp rats.
For example, I did a Flashpoint (dungeon) run with one other person after finishing the introductory planet. As it began, rather than buffing up and meeting the first mobs just inside the first hallway, we were instead welcomed aboard a luxury ship making the transit to the Empire homeworld (apparently those flying first-class do so through hostile). The second-mate realized my partner was Sith and kowtowed, telling her 'what an honor' it was to have someone from the Academy of Korriban aboard. I, being an agent of Imperial Intelligence and with no love of the Sith's sadistic ways, chastised her for doing such.
The multiplayer conversation system is basically a dice roll to decide who says what they want to say after each player has chosen their desired response. This determines how the conversation progresses, but each player gets the appropriate light/dark side points for their decision. In practice, it can lead to some entertaining yet ultimately inconsequential conflicts of interest: After receiving an encrypted message from the Grand Moff ordering us to seize control of the ship in order to intercept a Republic cruiser, we confronted the Captain. My Sith counterpart wanted to simply strike them down, but I spoke first and convinced them to cooperate (my companion wasn't happy with my decision either).
My view of my character evolved naturally given the fully voiced dialogues and options for realistic light/dark decisions. A light-side Jedi Knight or a dark-side Sith Warrior is relatively self-explanatory, and I imagine few players would deviate from those paths, yet I chose a different route. A light-side Empire character would seem odd until you view it as I did for my character: He has loyalty to the Empire and its citizens and an underlying distrust and dislike of the Sith. This meant I often acted with mercy or compassion in my dealings - though oftentimes 'mercy' meant killing someone quickly as opposed to torturing them.
It's notable that the dialogue system is in place for every quest on every world, too, though most don't involve as much variability as the Flashpoints besides often being able to kill a quest-giver rather than let them go. The quest lines are varied enough - the few quests that asked you to kill X amount of bad guys were usually auxiliary to the story-driven quests - you could skip them, but you'd miss out on a fair chunk of XP. In regards to the stories within single questlines, you know what to expect if you've played Dragon Age and KOTOR. People with problems and slight twists here and there when secondary characters are introduced.
The system to encourage grouping in otherwise soloable areas is interesting - you earn 'Social' points whenever you have a multiplayer conversation. In return, you can use those Social points to buy items that serve a fun or... social purpose, such as dress clothes or fireworks. The tradeoff is the now-and-then lack of control over the story, as exemplified in my Flashpoint example, but in the end most small quests would come to the same conclusion anyway. It's worth noting that it's especially rewarding to group in this way as a single group member can turn in a quest and save others time, as the others can 'holocall' in to join in the conversation, and thus complete the quest, while they're off doing something else. Bioware has even put in the effort to modify these conversations to consider whether you're a hologram or not (you can't physically intimidate an NPC if you're actually miles away).
Overall, the game is in stable condition, with a few bugs here and there, but nothing that stopped me from trying/enjoying everything I wanted. The companion system is neat - you can send companions to craft items and get materials in addition to selling your 'grey' items if you don't need them at your side in a fight. The PvP was a little poor, especially for me since my class relied heavily on the cover system, which didn't work well in the arenas. Lots of balance issues, perhaps, but overall it was impressive for being a month from release, and given the magnitude of this beta weekend I'm guessing they'll probably have a smooth launch. Maybe I'll pick it up a few months in, depending on what people have to say about the late-game experience.