As you know, last year's Bones finale was a disappointment in a great many ways. They promised change, but instead it all turned out to be a dream inside Booth's head, which was frustrating for a lot of fans. The dream was creative, no doubt about that, but it really didn't add much to the storyline as a whole other than having Booth realize that he loved Brennan. Which everyone already knew anyway.
This year, the finale was much more of a big change and one that served a purpose since a few things really have shifted this season. Booth and Brennan finally crossed the line only to be beaten back by Brennan's insecurities. Angela and Hodgins are married. Cam's moving on with her daughter and with a new boyfriend. The stories did all seem to be moving toward some things shifting around, and so while the case itself wasn't terribly interesting, it was a metaphor for what was happening to our beloved characters: they had to let go of their hoarding!
The ceiling crashes into a little boy's room with huge piles of junk and body parts coming down. The team is called in to deal with an agoraphobic "hoarder," a man who collected a variety of things obsessively and refused to leave his house. There were animals living up there and fans on to try and contain the smell, but it didn't help. The landlord tried to evict him and his former co-workers tried to get him out of the house, but nothing really worked.
Honestly the case isn't that important. It turned out his girlfriend/co-worker accidentally killed him. She forced the window open and he panicked and she pushed him into a fan. It cut him up and then dropped a pile of junk on top of his head, and he starved to death, basically. Messed up. There are some red herrings from the landlord and a fellow hoarder who stole an item from him, but what he really does is represent a major plot point. Booth and Brennan hoard one another, they are incapable of movement and change because of their ties, and in some ways must be "set free" of this obsession.