So When I first saw it, I was a little dissapointed. But the more and more I think about it, I actually really liked the end. Thought I'd make a list of all the amazing things.
Bold ones are the ones that were really awesome
1. Epic Jack/Locke battle . 2. Richard's first gray hair . 3. Richard being one of the ones who escapes .4. Hurley taking over . 5. Ben being second . 6. Cliff faces crumbling into the ocean . 7. Giacchino's music . 8. Rose and Bernard standing up to MiB . 9. Opening sequence . 10. Ending it with Jack's eye closing . 11. Leaving enough open to ponder over (Hurley, Ben, Desmond, How the world reacts to Ajira returning, Richard's off island life(and death))
So, my one gripe: I would've had them all getting prepared for something in the church before disappearing in a flash of light. Someone says "So here we go...again." Then flash to Jacks eye opening and other characters eyes opening as the whole series loops.
So it would end with the beginning. And you have no choice to watch it all over again.
But over all I'd give it a 9.3 / 10