House does heroin with a patient, and wakes up in a burning building with the other guy dead on the floor next to him (od). The rest of the episode is mainly House hallucinating people from his past and having conversations with "them" about his life and choices.

House apparently dies in the fire, with dental records confirming it's him. After his funeral, Wilson finds out he's alive & managed to fake his death. In the last scene, Wilson and House set off on motorcycles to have a buddy bonding trip before Wilson dies from cancer.

To start with, most of the episode wasn't great, but it was all right. Average to a little below average. The internal monologues were a decent device to have House reflect on his life, and it allowed them to bring back some pivotal ex-cast members like Kal Penn, Anne Dudek, Jennifer Morrison, and Sela Ward (not a cast member, but played House's ex-wife for a season). That said, the writing wasn't near sharp enough to make this work. House hallucinating Amber and conversing with her in his head called back to the two-parter that killed off Amber at the end of season 4. The writers used the same trick then to much greater effect. And, if House is really conjuring up people from his past to play devil's advocate/act as angels on his shoulder, Cuddy almost certainly has to be one. I'm assuming the lack of Cuddy is due to Lisa Edelstein being unwilling to come back, for whatever reason.

Also, spending most of the episode inside House's head completely neglected the rest of the cast. Wilson and Foreman had a few short scenes, the rest of the cast basically had the episode off. Absolutely no payoff for anyone who liked any of the current supporting cast.

As for the twist ending, ugh, We're supposed to take House faking his death to be a redemptive act. Right before the building seemingly crashes in on him, he comes to a realization that he can change and make different choices. He seemed to be passively suicidal up to this point - content to let the fire kill him - so choosing to live is framed as a change of mindset. The problem is that it's the same old crap he's always pulled. The character has always been self-destructive & the writers increasingly resorted to deus ex machina macguffins to let him get away with it without the full weight of the consequences. Faking your own death isn't noble or heroic. It's cruel to the people who mourn House and cowardly in that, once again, it lets House walk away from the consequences of his actions (jail time, mostly). It's not convincingly established that this will lead to meaningful change or even that the character can live without Vicodin and puzzles. The ending is supposed to be House's redemption, but it seemed to me more like a furthering of the status quo.

In part, the problem with redeeming House is that writer's let did this sort of thing before and it never took, probably because the people in charge of the show were scared to change the status quo overmuch. Wilson severed their relationship before, without it causing this much reflection. House gave up Vicodin and tried to be a nicer person after his stay in the institution. House's behavior landed him in jail. The problem is that the writers mostly treated this occurrences like sweeps month stunts (which they were) and House went back to his old ways relatively easily,

Also, for House to survive the fire and fake his own death, he basically has to become a super hero. He had passed out from doing heroin and woken up in a burning building. Later, he falls through a hole in the floor and drops to the level below. He lays there awhile surrounded by flames, so we can assume he's suffering from smoke inhalation. And then Wilson sees him at the front door as the building collapses on top of him and explodes. Somehow, in his condition, he managed to get to a back door very fast, walk out unnoticed, and somehow sneak into the hospital (or the coroner's office?) and switch his dental records with those of a recent patient? Wow.

The feel-good swerve ending also invalidated a speech Wilson gives earlier in the episode about teaching House how to live without him. And they never did explain why the building was on fire in the first place or any of a dozen other questions).