As far as the ending goes, I’m of the mind that it’s not over. There are too many questions left, in particular the extra 2 second ‘ending’ if you happen to make the ‘right’ choice. Just like with the Asari bartender on Ilium who turns out to be Liara’s mother, in the Mass Effect universe, 1+1 tends to equal 2.
Without spoiling too much, I firmly believe that the entire end sequence is just a product of Shepard spending way, way too much time around Reapers. He’s indoctrinated, and your final choice determines if you give in, or resist. There’s only one right answer. Even then, the choice is moot if you don’t have a strong enough force.
The game itself is great. The characters, the stories and the tension runs throughout the whole thing. There are emotional moments involving beloved characters, as well as new plot twists which keep it from being just a wrap up. The gameplay is a mix of the best elements from both previous titles, and the only thing it’s really missing is hacking/bypassing. I suppose, given the urgency of the game, sitting there sifting through code breaks the atmosphere, but it’s something I for one miss.
Your choices from previous games do not, as far as I can tell, impact the potential War Assets you can collect throughout the game. No matter what you picked before, there are options worth the same number of points in the end. What they do, however, is determine how those points get distributed. You get very different reactions if you saved the Rachnii queen, or shot Wrex. While the points may end up being the same, and the storylines to get them are, the actual experiences along the way differ rather dramatically. Choices made in DLC content from earlier games also comes back, sometimes with surprising results.
Overall, I would highly recommend ME3, so long as you don’t operate on the assumption that the end of the release game is the end of the story. Bioware has already stated that this isn’t the last we see of Shepard. As such, the ending is more like the end of Halo 2. We know theres more coming, we just don’t know what. The multiplayer is also oodles of fun, and that’s coming from someone who traditionally hates online shooters.