Oh, sweet!
Overall: The EC is a huge improvement over the previous endings. Answered a lot of the WTF-type of questions. The starkid came across as a lot less sinister and more of a AI construct. While I thought the Indoctrination Theory was a lot of fun and didn't really think it was what they intended, they definitely swept that under the rug. My first game I had wondered if Shepard was hallucinating because it was such a disconnect from the rest of the game. Now it flows better -- she comes across as more coherent. I'm greedy and wanted more out of the ending, to see an actual reunion happen, not just implied, but y'know, at least the last image of the LI is hopeful instead of weepy or whatever. I've seen lots of people say they like the ambiguity, that it leaves the reunion to their imagination so I guess Bioware found a nice middle ground.
To be honest, I had wanted what they gave us in the end of ME1. Big triumph, bad guys defeated, Shepard emerges as a hero and everyone starts planning for what-comes-next. I didn't really feel like a hero at the end of ME3. I really did not like being railroaded into self-sacrifice. It should be one of the options, but 3 out of 4? They really wanted to kill Shepard off, eh? I do think that they could have left some wiggle room for Shepard surviving in Synthesis with really high EMS. Reaper technology upgraded the geth and EDI. Shepard could have been upgraded into a different form, I guess. (There is an image of Kasumi and Keji face-to-face in one of the synthesis outcomes and I just thought that kind of scenario should be possible with Shepard appearing to the crew like that perhaps.)
Anyway, the game is now replayable without having to lean on head canon. I don't know if I want to buy their DLCs because it kind of seems pointless. I will be shallow and just say that unless it involves more content with the LI, I don't really care about stuff like helping Aria take back Omega or investigate more Reaper lore or whatever. (I had bought every single DLC before. I just feel somewhat burned this time around.) I'd definitely buy new armors though.
Here are my three gals. I'm very sastisfied with the way their respective stories ended, which fit their personalities well. Control ended up being my favorite because it was such a messy, difficult journey that Shepard actually ascended above all the pettiness to do some real good.

^ My canon. Love her. Finished the job she started. Had 7k+ war assets so everything ended on a high note. Not really much more I can say. The collateral damage is unfortunate, but the Reapers had to go.

^ Although Judith was created for exploring the Jacob romance in ME2, I decided to RP her as pro-Cerberus with a strong human bias (in order to fill in the blanks on why Wrex wasn't around, no rachni queen, etc). She went from being abandoned by the Alliance in ME2 to being burned by the Illusive Man and Jacob in ME3. None of the pro-Cerberus decisions paid off in ME3, which was disappointing. Everything was an uphill climb from there.
Wreav was bullheaded and war hungry. With the data gone, it was futile to work with the krogans. Legion had previously been sold to Cerberus so there was no connection to the geth, just yet another race gearing up to destroy another for survival so Judith had to pull the plug on the geth. Thessia got overwhelmed, another domino toppling over. And then there's humanity, beytrayed by the Illusive Man's lust for power. (You know it's bad when Javik is the one giving Shepard a pep talk.)
Choosing control was like watching a phoenix rise out of the ashes. Judith had struggled to get the races to work together, but now she had finally become the ultimate leader. No more oppression or being preyed upon, Judith was now there to defend the weak, to put an "end to the bickering of the many." Jennifer Hale's voiceover was so perfect. It really felt like this was
Shepard's Story, not the galaxy's story. I definitely saw the parallel between leaving David behind on the
Overlord project to prevent future wars and Shepard sacrificing herself
in the same way. This was a very empowering game. Easily my favorite because it ended on such a strong note.

^ She was all about giving people a chance at a future without limitations. She fully encouraged Joker and EDI's romance. She sided with the geth so they could have a chance to break free from their oppressors. Not my favorite game, but synthesis made sense. Didn't love the husks, but I can see how it would amuse the devs to leave it in.

It sucked leaving Garrus behind. She couldn't give him children, but she gave him a chance at immortality.