Yep, back and forth with me, too. I think CP had it best, good job on the pandering.  The show hit many emotional and fun notes just right, so I enjoyed it.  But I didn't realize just how weak it was storywise and intellectually - frankly because my memory of prior seasons is just vague.
I think I'm pretty clear on this though:  Rather than leaving ALL those billions of Island story issues unresolved being "meh," it is indeed an unforgivable sin.  And rather than the "twist" ending being a mild cop-out, it is the antithesis of all that went before it.
In other words, a completely typical beloved dramatic series finale.  
