I liked the episode.
Initially I thought the guys in the diner were feds or hitmen, but after re-watching the ending a few times, I think they were nobodies. Tony was on guard and we were watching and judging the character of those men through his eyes and based on his suspicions. He'll always be looking over his shoulder and never feel safe.
It's just another night in the Soprano family. How many times have we seen Tony involved in a hit/something gruesome, or the family have to deal with tragedy, only to end up at the dinner table talking about their day like any other family.
The loose ends were tied up with the family. We saw how far Jr. has fallen. He used to run North Jersey, now he barely knows his name. Janice tries to carry on without Bobby (with financial help from Phil's crew). Carmella and Tony wanted their children to have lives outside the mob, but to keep AJ out of the army he's now working for a movie company financed by the mob, potentially opening a club, financed by the mob, etc. He basically abandons all his feelings about doing something bigger (Afghanistan and CIA) for a BMW and a shot at a movie deal. Meadow is marrying into the mob. It just shows how firmly entrenched they are in their mob family.
I like the idea of everything going to black meaning Tony was killed, but I just think it meant the end of the Soprano's as a series. Tony is back in power. Little Carmine will likely take over the NY family now and he and Tony are on good terms. The few guys close to Phil basically gave Tony the go ahead to do whatever he needed with Phil...so they weren't all that loyal to Phil either. Who would have it out for Tony? Everything is as it should be...
And, their options are completely open if they ever want to revisit the story
I'm not one of those people that gets all of the symbolism and deeper meanings in books and shows, so I may be totally off base. Just my take on things, FWIW.