I, for one, liked the endings on my first playthrough, and I got to say, for my character they turned out pretty bittersweet.
I chose to spare Loghain, and was pretty surprised to see Alistair react so forecully, but it wasn't in my character's character to change his mind at that point. Alistair was my character's BFF (or so he thought), so that was a blow for him. My character was also in love with Morrigan, but didn't want to create a darkspawn monster, so she left him as well on the eve of battle. My character was sure disappointed, but I definitely wasn't. I mean, it's a sad story, and definitely not the ending I would have wished for my character, but I still like it because it was consistent with the characters and the setting. Well, that Alistair suddenly found the guts to actually do something was a bit surprising, but still...
Since this game is more influenced by realism than most other fantasy games, it's actually pretty nice to see a game ending where the world goes on, and where new problems constantly arises.