Mass Effect 3 contains some of the best written storytelling in videogame history. Unfortunately, the final moments of the game also contain some of the laziest and worst moments I can remember.
Up until the last half hour or so, the game is a breathtaking rollercoaster ride where the majority of the plot points from the previous two games are tied up skilfully in a satisfying way that connects well with whatever decisions you'd made in the previous games. If you'd saved this alien race, or that scientist's data, or sided with this faction over that faction, it was all remembered, recorded, reacted to, and made the universe seem unique to your own experiences.
The ending though makes little sense, features a badly written Deus Ex Machina ass-pull, and has events with repercussions that seem to render most of what you've achieved in this and previous games pointless. It left me feeling confused, annoyed, and gave me no sense of closure. The much trumpeted "TAKE BACK EARTH" slogan on all the advertising ultimately felt ignored, and the final message players are left with is to "Buy DLC" to continue the commander's adventures.
At that point I realised that though it was a rollercoaster ride, a lot of the previous games intricacies had been stripped away, railroading the player through what boiled down to be a big bunch of fetch quests. (31 quests (out of a total of 68) were fetch quests. Mass Effect 1 had more quests 73, and only 5 of them were fetch quests.)
A good story (until the end) but it doesn't really do justice to the series as a whole, and the all pervading sense of railroading only highlights what's been stripped out of this game.
For:
Fun Combat.
Giant Setpieces.
Great and funny voice acting.
Brilliantly written endings to Geth / Quarian / Krogan storylines.
Against:
No Ship Upgrades
No Mako / Hammerhead Planet exploration.
An important squadmate is held to ransom as Day One DLC.
Terrible ending to the overarching Reaper / Humanity storyline.
Less quests than previous games, and nearly half the quests are fetch quests.
Previous Journalist characters are removed in favour of a Tie-In with IGN.com
No Planet Scanning / Resource Gathering / Hacking minigames. Feels like the game is *only* combat.
Very small number of squadmates (Only 2 if you didn't save everyone in previous games and you don't buy the DLC character)