I just beat the game. Didn't really mind the ending to be honest. Or at least not the definite ending, some of the things leading up to it could have been handled a lot better. But hearing people bitch over it made me postponing playing the game for a really long time and made me think the whole game was going to be terrible. It's not.
The thing that strikes me the most when playing Mass Effect though is how much I really love those characters and that universe. I never get invested in fantasy world otherwise but this one I've really enjoyed throughout the years. It's weird how BioWare manages to write some great characters and great lore, while being absolutely terrible at writing the bigger, over-arching stuff.
Buy the Citadel DLC if you like the characters. They did an awesome job with that.