New endings don't really offer anything new. You see your crew escape and then each has the same slideshow with different effects and narration depending on the endings you chose.
Control: Shepard, now the new Catalyst, gives a speech about how he/she will essentially be the new babysitter of the universe. Slideshow depicts random characters and a tribute to the fallen
Synthesis: EDI gives a little speech and the people depicted in the slideshow have green eyes.
Destroy: Admiral Hackett gives a generic speech about making your own choices, etc. etc.
Oh yes and the secret 4th ending
Rejection: You are now given dialogue options to say "fuck you" to the Catalyst's logic. If you select the new refusal dialogue, the Catalyst says in a demonic voice "SO BE IT!" and leaves. The cycle continues and the Reapers wipe out all life in the universe while you can do nothing but watch as you die. Liara leaves a message behind and in the end a new female Stargazer says that with the help of that they were victorious in the new cycle.
You also get this ending by shooting the Catalyst, proving that BioWare is obviously pissed at people for bitching about the endings and making them do more work.