Cyrus isn't really a comedy, though I wouldn't blame you if you have that impression before seeing the movie. Both Jonah Hill and John C. Reilly have been in a lot of comedies lately (though Reilly is fairly well-known for more serious movies like Magnolia and Boogie Nights), and the trailer doesn't do much to dissuade that notion. It does have some parts that are quite funny, but it gets more serious as the movie goes on, and is quite touching and raw at times.
The story is about a divorced, lonely man (Reilly) who meets a seemingly perfect woman (Marisa Tomei). The only problem is that she has a live-in adult son Cyrus (Hill), and they're co-dependent on each other to the degree that Cyrus instantly hates the new man who (in his mind) is going to take his mother away. His solution is to sabotage their relationship.
That sounds like the set-up for a broad comedy in the vein of Step-Brothers, but Cyrus sticks fairly close to its indie sensibilities. It's filmed in an almost documentary-type manner, the situations never really get too over-the-top or absurd, and the relationships remain the focus of the movie, throughout. The issues of co-dependency and parents and adult children having a hard time letting go of each other is treated pretty seriously.
Cyrus was one of my most anticipated movies of 2010, and while I can't say it was as great as I hoped it would be, I ended up being pleasantly surprised by the tone it struck. I say keep an open mind and check it out.
