Part One: No Spoilers.
So you ready to kill the Reapers? Not so fast, here comes ME3, reminding you that team effort is necessary. I mean, dude, there are tons of Reapers! Humanity can't do it alone, even if The Illusive Man thinks so.
The start is kind of abrupt, but then you get into it. Story is solidly well written and characters new and old are fantastic to have on the ship and bump into while you assemble the best war militia the galaxy has ever seen.
Also, I think this is the most complex they've actually made Shepherd. You delve into what breaks your Shep's heart and how to pick the hero up and start punching reporters again.
Gameplay is fantastic. Everything is smoother than ME2, which already seemed like a godsend compared to ME1, and leveling up feels a lot more compelling. Powers are great, and strategy is still at the forefront. That is, if you're not doing the narrative version which weakens everything. Then you can do whatever you want.
And still scan those planets, but with half the tediousness! Seriously if you want to win you really should scan those planets. Just sayin'.
Multiplayer helps you with the end game part for ME3, and even if it didn't it's worth playing. Now if only I could finally get my friggin' quarian engineer I'd be completely satisfied with the multiplayer. Aww darn.
Don't forget that this is the end. Some of your favorite people will sacrifice themselves, so be ready. I've talked to grown men who admitted tearing up at parts.
And some of you, like me, will find it hard to say goodbye, even though you know you have to. I was weeping and sniffling and wailing when I was saying goodbye to my squad before we did the last battle. I am one to get super attached to fictional universes of this proportion. This was it. I will never get a chance to shoot things with Garrus, smash things with Wrex, or pontificate with Tali possibly ever again. I am going to miss these characters.
Everything is extremely satisfying, and the end game is super epic. Until the last five minutes. When you think it's over, just escape before the credits roll. There is a reason the internet rage exists. However, this is less than 1% of the game, and luckily alt+f4 fixes it for you if you want.
Do I recommend playing Mass Effect 3? Yes. Sure, you'll get burned by the largest chunk of horrible writing at the end of the game, but there are so many other moments worth playing for that you'll kick yourself if you don't enjoy the other 99.5%.
Part Two: Spoilers
NO SERIOUSLY NO LIE SPOILERS IF YOU DON'T WANT TO KNOW WHAT HAPPENS DON'T READ THIS.
I hope that works. People are touchy about that on the internet.
For those fans out there who have finished the game, I want to encourage you to think about the game as a whole and ignore the last "choices" part. I've been seeing a few arguments for this on the internet and I have to agree. Mass Effect 3 is more than just the last five minutes.
There are so many epic parts that I do want to relive again and I will. The little moments with Garrus, Tali, hell I even started to like Miranda and she got under my skin in ME2. There are things you didn't realize you love. Eve showing us female Krogan are the best! Udina taking a bullet because now everyone sees he's a legitimate dick! Lasering a Reaper face! Telling Cerberus to suck it over and over again! And of course, getting back with the man/woman/alien you love. My first playthough was a femshep dating Garrus, and it was sweet without rotting your teeth out. And there are parts I can't wait to play with my "Renegon" Obama shep and my full renegade Alexi shep with their different choices and outcomes.
A lot of us got burned on the ending. It's horrible. It's like a freshmen year philosophy major smoking weed on the quad defecated all over the end game and Bioware didn't bother to see where the foul smell was coming from. I totally understand. I've lost sleep over this ending, and I think I'm catching a cold because of that.
But there are too many great things about this game that I wouldn't want to miss as a die hard fan. It's worth playing the majority of it, especially if you know the ending is going to suck because then you know to avoid it. Focus on what made this a fantastic game, and it'll be a lot easier to forget that child VI that gave a whole finger to the universe by limiting our choices to nothing but suck.
Okay yeah I'm still bitter about it.
The only other legit critique I have is that I don't necessarily like how multiplayer is necessary to get a "decent" ending. Which isn't that decent and I hardly found satisfying enough to consider playing. So Shepherd possibly breathes for a second in the wreckage. Big deal. Doesn't mean Shep stays alive or is anywhere near the planet that the Normandy lands on to restart civilization as we know it. Fuck that. In other news, a whole bunch of people are now stranded on earth with no where to go and depleted resources. Yeah, there is no way that's going to end well.
Alright I got into the bad zone again. Look, loyal readers, please understand that I'm not trying to defend what happened to the end game. But there is a lot of stuff worth loving about this game, and now that you've played it I suggest you think about all the choices, dialogue, cut scenes, and fights you genuinely enjoyed. They have to outweigh what happened in the last five minutes enough that you cane play up to that point and then quit. You'll feel a lot better for it.