Watching Season 6 at the moment. Am pleased to report that picture and sound quality is amazing. But the absolutely first thing that I had to watch was "The New Man in Charge": the 12 minutes-long "mini episode" that follows up on the events of the series finale. And in twelve minutes we get to see darn nearly and maybe all of the still-lingering questions get answered! Wondering about the food drops, the "Hurley-bird", Room 23 and Walt? Well those and many more matters get addressed to satisfaction.
If you're thinking about getting this set soon, you might wanna drop by your nearest friendly neighborhood big box store and get it this afternoon or evening: they were going fast at the nearest Best Buy (in fact mine was the last copy they had and the nice lady at the register said people had lined up outside the store this morning to buy the Complete Collection and the regular Season 6 set that also came out today). If you're anything at all a nut for Lost, this is definitely a must-have :-)
(And I learned yesterday that the Lost Season 6 soundtrack CD will be out next month! Followed in October by the 400-some pages Lost Encyclopedia.)
EDIT 7:35 p.m. EST: I just found the hidden disc. Yup, there is another disc in this set and you have to look for it: it's not anywhere that you can readily spot. And this is a huge box set. I'm beginning to wonder if it might be booby-trapped...