Firstly... this game was incredible. :) A must play for any fan of choose-your-race/class RPGs. It doesn't need that high of a comp spec (my comp is a couple years old and it works fine on high def), and the voice acting is superb (save for slightly jarring mute!main character).
Final clocked time on first playthrough: 61hours 35mins, elf, mage, spirit healer/bloodmage, normal. Great work on Bioware in making a game almost as long as a Japanese RPG. The above time doesn't even count in the endless reloads. This game is a tough one, and if you have never played WoW before or similar rpgs that need LoS pulling and basic tactics then it will be even harder.
Gameplay: The gameplay was pretty outstanding. There's the usual stupid AIs, but not as buggy as NWN. (Look, AIs will always be pretty stupid and walk over traps. that's why you have to micro them). The tactics system, very similar to but an improvement on the FF12 gambits system, does help, but nothing beats micro. For those people bitching about needing an auto-pause when any party member hits 25%, try playing a healing class in WoW for a couple of years. The game is not meant to be easy and surprisingly enough, that made it even better.
Storyline: The main plot is pretty predictable if you've read any sort of high fantasy (particularly Tolkien) the mini origin stories are highly enjoyable. The game is dark fantasy though, and it shows - all the mini origin stories are terribly emo/tragic (save maybe for dwarf commoner, but that's because you already start off on the bottom of the barrel, your sister is a ho and your mother is a drunkard, you work for the crime boss, and you can't go any lower).
The only odd thing about the storyline is the remarkably convenient way every single person you go to for help has non-Blight related problems. :O Morrigan makes a sarcastic comment about it at one point.
The best thing about the storyline, however, is that there are very few black and white choices. As such there's no real alignment issue in the game (though you can do bastardy stuff, usually there can be a reasonable explanation). This was realistic and depressing at the same time.
Complaints: For all that the game is Dragon Age
Origins your origin actually doesn't make that much of an impact on the storyline, unless you are a human noble. This is particularly jarring for the dwarf noble storyline, which even on your return to your city there isn't much of a difference to the story as a whole. Would have been nice to have some significant choice changes: would make replaying better.
Characters: Amazingly enough, the characters were as likeable as an FF game, personable, +character development, +great voice acting. The character dialogues in party are fun, the choices can be hilarious (esp for Oghren) and the sidequests can be unexpected. As usual, the romance aspect is terribly awkward, esp the 'sex' scenes, but the other party members' reactions to your goings on later in dialogue can be funny.
Also, yes, there are lesbian/gay romances, though of the bisexual characters, the girl is crazy and the guy is a sex-mad murderer. Not sure how this reflects on popular perception, but I guess all the party members are deeply flawed in some way anyway (dark fantasy).
Hints: Force field is your friend. Let your tank get aggro, drop the field on him, and with any luck the boss/enemies will still be whaling on him without any harm. Also, if you intend to keep Zevran, make sure your approval with him is in 'Friendly' (or Adore, with the romance option) before you go to Denerim. Take Persuade at the very start, or you can't take it again later for some reason until very late in the game.
( spoilers ) Recommendation for people interested in the Alistair romance storyline: human, rogue, female noble, assassin---duelist
Recommendation for people interested in the most interesting origins storyline: human, dwarf, warrior noble tank, templar---champion
Recommendation for playing at higher difficulty levels: mage, arcane warrior---bloodmage
Recommendation for playing 'evil' (i.e. no Wynne in party): mage, spirit healer---bloodmage