I am not very big on the breath scene. I understand Shepard lives but it is almost a little too vague. Sure it would be great if Shep would live, but honestly? Give that man/woman her/his rest! They've been through so much, dealt with so much, swore their life to protect and secure, rescue and save. It is okay for them to now have their peace. It's sad they cannot be with their LI (if you don't choose Destroy) but you know what, life goes on. There can't ALWAYS be a utterly happy ending, it was a WAR! after all. How many other people besides Shep had to die for it? How many soldiers, scientists, Krogans, Asari, Quarians? They had families. They had hopes, dreams, goals. But there has to be sacrifices in a war.
I really don't understand all that hatred towards BioWare. They try, do their best, develop really deep, intense, emotional games. They try to please everybody, which is really hard since (especially) these days nobody ever IS happy and satisfied. They complain about one thing, then once it's changed, they complain that it's been changed.
Also, they do have deadlines, you know. They are a big company, they do put lots and lots of time and money in their game making. If some people think they fail so badly, why not try make a better game yourselves? In my opinion ME was the best trilogy ever, the plot was great, the characters were extremely well developed, the LIs were interesting, there was fun, laughter, tears, anger, you could make your own choices. I think there was nothing wrong with the endings whatsoever. Everybody had their choice whether to control the Reapers, to Destroy them or to connect synthetics with biotics. Now, what's so bad about that? Because Shepard didn't live (or ... well ... you know, in most cases didn't.) ? Because ... I really can't even think of any fundamental reasons. If you chose to control them, you take off into space, endlessly keeping them away from civilization. They are save. The threat of the Reapers is gone. There can be peace, cities can be rebuilt.
Then there is Destroy. You chose to destroy the Reapers, you wipe them out. They are killed, dead, gone. Synthetics as well, okay but they do say they can be rebuild. Everything can be restored. The planets are save. And Shepard might even still be alive.
Now, then there's Synthesis (it's what I chose). You choose to connect biotics with synthetics. Every race already depended on synthetics in almost every case, they were already part of them. But they lacked the understanding and knowledge of human emotions. Now humans (& aliens) still needed synthetics to do many things, but now that they are connected, they have the advantage of doing all this by themselves. Also, synthetics and biotics now can live peacefully side by side. The Reapers even help rebuild the cities, the damage that's been done. The races go a step further in evolution, they gain enlightenment. (And EDI lives, yay!!) Shepard gave their life for a better purpose, for a better life, a better ending! In my opinion it's the most beautiful and ethically correct choice.
Now, that is just my opinion about the game trilogy itself and how it ended.
ME4 - I would DEFINITELY want to see more of Mass Effect. I am not sure if having Shep in the game would be necessary to make it a good one. As I mentioned earlier I think Shep deserves their peace. Shep's story is over. It's come to an end. They fought for what they believed in, for their main goal (to save the planets) and succeeded. I also don't know how they would do it. Have Shep back I mean. What if several people did not manage to save him/her? Will it simply continue with a new character? Or even though Control and Synthesis did not get a breathing scene, is there a chance Shepard may still be alive? I don't know.
I loved Shepard. I cried so badly when he/she died. They became some sort of alter ego, a friend. A sister/brother. Shepard became YOU! YOU became Shepard. But I would also be very interested in seeing a new hero, a new character who meets other new characters, faces other new challenges, enemies but might meet some of our old friends during their journey.
Either way, I am sure BioWare will not fail to impress again, if they are working on a ME4. Now, that is just my opinion. I understand not many will agree and respect that many also were not satisfied with the game, the ending, whatever. I just hope that they might have a better experience with an upcoming new ME, or simply a different game in general.