Just finished playing through the extended cut with my female adept Shepard. First change I noticed was right when you're charging the beam but I started back at the point of no return anyway since that's what I'd seen suggested beforehand. Overall I'd say the new ending left a much better impression on me and pretty much did everything I was hoping for the first time around. Other than a few extra scenes mixed in from there to the final choice most of the new material took place right before the credits in one long cutscene. Honestly if they had come out with this in the first place I think a lot of the criticism the ending got wouldn't have been there. (Well, other than issues dealing with the Citadel segment itself and the Catalyst.)
I have to laugh though at the extended conversation with the child since some of the questions Shepard can now ask felt like they were only there as a direct response to the outcries of the fanbase. (Yes, there's more to him now. This probably doubles the conversation if you take all of the extra options like I did.) Even if you don't like the responses he gives or the fact that it does explain a lot more about the Reapers than some people would probably want, it does try to answer a lot of the questions I'd seen running around over the last few months so I've got to give it that.
And as I said, I did like that final scene before the credits. I got one narrated by EDI and it focused on my choice and what happened after the Synthesis ending with a lot of still images and a CGI cutscene mixed in dealing with the surviving crew. Combined with the first new scene when charging the beam I though it did a much better job of cementing the fact that Liara was my LI in those final moments.
Oh, and baby/child Krogan! Can't forget that.
So overall I think the extended cut is a much needed addition to create the right sendoff for the trilogy and Shepard. At least with what they had to work with dealing with the 3 choices and the backlash against the Citadel segment at the end.
Shepard refuses to make the choice, and then it cuts to that same planet you see in the normal ending where the Normandy crashed and hear Liara's time capsule. Basically, the current ME galaxy loses but allows the next one to have time to find a solution. End cutscene with the Stargazer is now a woman and the content is different, but it suggests they found peace anyway.