As a longtime fan of the Mass Effect series it is painful for me to give this game such a low rating. The fact is that while the majority of the game is very good, though not without its shortcomings, the finale of Mass Effect 3 is atrocious; riddled with plot-holes and contradictions, vague, unsatisfying, non-sensical, and ultimately left me feeling bitter and empty.
The most obvious strength of ME3, like previous installments, is its characters. The voice actors bring them to life masterfully (if of course you ignore the shameless inclusion of a certain IGN personality), and they are rounded and interesting enough to make you genuinely care about them. The story is fairly simple, but easy to follow, and grand in its scope; after discovering the plans for an ultimate weapon, you must rally the races of the galaxy, resolve long-standing grudges, and bring them together to combat the Reapers while this weapon is constructed. There are some exciting, cinematic moments, and it is very satisfying to see events and characters from the previous games melded into the narrative, even if some of these are only token, or cameo, appearances. The combat is very similar to ME2, with various tweaks that improve the system. It's much more challenging this time around, and I found myself constantly experimenting with my load-outs right up until the final moments.
The quest system is very poorly implemented. Many scanning side quests will be heaped on you just by overhearing conversations as you walk through the Citadel, and there is no way to track your progress. With the lack of any real context, it makes the side quests rather tedious. There are also very few characters available as squadmates, when compared to the previous games. Two of which are only available about half way through the game, and another only if you buy the From Ashes DLC. Generally, I couldn't help but feel that many elements of this game were clumsily put together, but it all seems to work nonetheless.
These gripes, however, are irrelevant when held against the ending. What truly makes it such a travesty, aside from all the ridiculous lapses in logic that the ending is rife with, (and all the lies it now seems we were told by Bioware prior to release), is that it totally overshadows and negates the many positive aspects of the series that have come before it. All the characters you've come to care about, all the relationships you've built, all the hard choices and sacrifices you've had to make, and all the problems you've solved, ultimately all mean nothing. This is the reason for such a low-scored review, and the reason why so many others are doing likewise; the aspects that made Mass Effect great are all scrapped and tarnished in the final hour in favour of a pseudo-philosophical, nihilistic, non-sensical conclusion. Bioware even have the audacity to leave you a little message after the credits role telling you to buy more DLC. Disgusting.
The 30 hours of enjoyment you'll get from most of the game are not enough to justify the final emptiness it will leave you with. It is simply not worth it.