The extended cut is significantly better IMO than the originally released game endings, though it still has the same press a button and your decisions didn't really matter just the readiness rating problem. I kind of assumed that would be the case since it would require a lot more work and money to fix that major flaw.
Still, I have to give them credit, if they released the extended cut stuff with the original release, I would have been much less critical of the ending. The extend one I played through with my first play through save felt more like a proper ending to the ME series and at least did a better job of seeing some of the aftermath of your a,b,c,d button select. FYI the endings on Youtube are only from the star kid part on. There were some changes to the get to the beam part like
your team getting evacuated from the planet via the Normandy. While that scene worked it opened up on small issue for me of why Harbinger didn't zap the Normandy when it was right in front of it.
For me it was worth playing the end of the game again. For some reason my last save was from the Illusive man base. I lost the save I had before the final mission and the autosave from the citadel end part not sure why maybe because I did a newgame+ using the profile so the game erased it? But either way I was glad I went through it. I like new endings, it is the same as before but with a little bit more of what happened to everyone so the end didn't feel so WTF and hollow.