The fourth season of Bones gets us in touch with the characters on a deeper level than previous seasons, with many more serious episodes than the previous seasons, but also a lot more funny ones. It generally follows the same formula as the previous seasons, Booth and Brennan working together on cases, solving murders and such like, though there isn't a 'main' plot point such as Gormogon or Max Keenan in this season, instead it focuses more on the main characters and their relationships, though it does feature an episode with a return from the Gravedigger from the second season.
This season shows remarkable the growth of Brennan as a character, and she has become a lot less two dimensional compared to earlier seasons, and whilst this could detract from her charm slightly, I find that it makes her all the more endearing. We get the rare insight of the vulnerable nature of Booth in a couple of episodes which also shows his growth as a character, and it's refreshing that the characters haven't become caricatures of themselves as happens in other tv shows.
The lack of a certain character from the previous season is disappointing, though the writers make up for it by including several interns, each with their own quirks, all of whom feel like part of the team by the end of the season.
Overall, this season of Bones is both dramatic and amusing, in a perfect blend to get the right amount of viewing pleasure. Though it isn't tied together with an underlying plot point in this season, the 'will they, won't they' of Booth and Brennan keeps us guessing enough to want to keep watching to the end, and for a finale the twist in this season is as entertaining as it's ever been. The best season of Bones so far.