I watched the Destroy ending over my lunch break. My thoughts (spoilers follow, obviously):
The extended cut improves the final sequence from Bad Idea/Bad Execution to Bad Idea/Decent Execution. The fundamental problem I had with the ending still remains. The Star Child is still a stupid idea. The Reapers' goals ("We're a race of synthetic lifeforms who periodically wipe out organic lifeforms before they can create synthetic lifeforms that will wipe out organic lifeforms.") is still completely illogical and ######ed. I still reject the very notion that synthetics and organics cannot coexist since I accomplished exactly that by peacefully resolving the Geth/Quarian conflict in my game. It's still left unexplained how my squad members from London magically appeared on the Normandy. Showing the Normandy crash landing on the jungle planet now makes even less sense since apparently the crew was able to repair the ship and leave without issue. That sequence adds nothing to the narrative.
My other big complaint -- distilling a trilogy with dozens (hundreds?) of decisions down to a simple Red/Green/Blue choice -- doesn't appear to have been resolved. From what I can tell, none of your big decisions have any effect on the ending sequence other than showing a few still shots of characters who may or may not be dead depending on your previous actions.
However, the extended sequence does answer many of the questions the original ending left us with. We know now that the Citadel and the Mass Relays weren't destroyed, only damaged (but left in a state where they can/will be repaired). This certainly allows BioWare to create future Mass Effect games set ~50-100 years after this trilogy where the status quo is essentially unchanged. This is good.
Had this been the ending that originally shipped with the game, my reaction would likely have been one of mild disappointment at the wasted potential rather than outright hatred. With the new ending, the concept remains fundamentally flawed, but at least the story is now competently explained. I suppose that's as much of an improvement as we could reasonably expect.