I can't think of a better finale to a show. Honestly I can't even think of anything that comes close.
Yes some people may say why didn't they check the boot, but lets not forget the entire time that Walt was there, they thought they were in complete control. They assumed Walt was desperate, and whatsmore when they saw him cry for Hank they thought he was weak. Their only worry was perhaps he'd rat them out, never that he'd attempt to kill them. They were amateur gangland trash and got their just desserts in the end.
Jesse choking out Todd was also bloody brilliant, and Lydia copping the ricin was perfect. Having to contemplate her own death for hours after threatening Walt's baby daughter was a fitting end for her.
I honestly don't know how any show is going to top Breaking Bad. From the first to last episode everything was just so well scripted and thought out. Not once in the whole series did I stop and think they are just making this up as they go along, or that they'd lost track of who the characters were. All the characters were completely broken by the last season, but they were all still themselves.
Just a great show. Think I'll start watching again from the start just to absorb it all again