Funny People has its moments of humor, intelligence, depth, and emotion, but unfortunately, not even Apatow can make a three hour movie out of moments.
The real flaw in this movie is that it's too spaced out to have any real depth: it tries to cover too much ground, and as a result, the whole pool becomes shallow. It's physics. The first hour of the movie is traditional Apatow cock comedy, but then someone at the helm flipped the drama switch and turned the remainder of the film into a tragicomedy with nothing of interest to say. This film unfortunately falls into a trap my 11th grade English teacher used to describe: it acknowledges the complexity, but it doesn't explain it. Apatow creates complex characters with a sardonic edge, but I never found any of the characters particularly funny, dark, or valuable. They were all too stale to connect with for me.
To go back to an earlier point, Funny People is an absurdist tragicomedy, featuring bizarre plot turns and characters, sardonic humor, and a noticeable lack of resolution. The problem is, many elements have to go right for the whole tragicomedy deal to really come together on the level of Beckett or Ionesco. Most of the humor is reasonably funny and hints at larger issues of emotional insecurity, sex, etc., but there's plenty of lame sex jokes that failed to really have an impact on me and distracted me from the plot. On the other side of the coin, the drama of the film, Apatow introduces interesting characters and concepts but fails to deliver any meaningful message with them.
The acting is decent, and the script is okay, but I think Apatow was aiming for the stars and landed somewhere in the Lifetime-original-movie-that's-funny-for-the-wrong-reasons atmosphere. It's a fine effort to create a comedy with depth and purpose, but it's off the mark.