Unlike most of these reviews I have completed the game. WTF Endings! No spoilers.
Some might say who cares go play blah, blah, blah, if you don't like it. The fact is I am a huge fan of the first two. Even bought the Collectors Edition, that was a huge mistake.
The Good: Combat, Characters and Engaging Character Interactions.
I thought the combat was fun. It's pretty much the same as it was in ME2 so if you like that you'll be happy with combat. The characters are the real draw here. You'll want to see what happens to them. They interact with each other and Shepard in endearing dialogue and scenes.
The Bad: Story, Music, Mission Timers, Endings.
The story for me was the worst, I haven't seen something this stupid since I last watched G4. The game has a very dark and heavy atmosphere to it. I understand that the galaxy is under siege and millions are dying everyday but I felt like it was too gloomy. Even the Normandy looks and feels diffrently. Shepard is pretty down throughout the whole game, though there are a some smile inducing moments.
The music, I believe was composed by multiple Composers and it shows. Instead of the synth music they had in the first two this one has a Classical sound which seems out of place.
Some missions are time based and you can miss at least one Character that I know of by inaction. I encountered missions that I couldn't fufill, leading me to believe that I had missed the timeframe in which to complete it, even though it was still given.
Now to the ending this is where all your hardwork, and hours upon hours of playing, through three games, comes to it's bizarre conclusion. I won't spoil it but if you like gloom and doom or "realism" or WTF moments you'll enjoy this. If however you are like me and wan't to see Shepard's journey and choices honored you will be bitterly dissapointed. If your not invested in the series you'll probably enjoy it. Only a massive dlc can redeem this series in my eyes.