Like all comedies, its mainly a question of preference.
You may not find the movie overly funny, or you may.
I could maybe say that the movie slows down or becomes a little convoluted near the end when there's conflict within the relationship between Zooey and Peter and furthermore with Sydney.
But like I said at the beginning, I might be a little bit bias. I can't necessarily call it a comedic classic as its too early and too "obscure" of a comedic film to have that big of an impact yet, but I know that years down the road, I'll probably look back at this film as one of my favorite comedies when I was in my late teens/ early twenties.
I don't know what it is, but Rashida Jones is very good at playing the cute, modest girlfriend.
I think its a fun relationship though probably not the best relationship ever done on screen.
The main draw of the movie is the emphasis on bromances and Peter's quest to find a friend. He gets set up, he does online friend finding, he actually goes out with a guy who confuses their outing as a gay date. Then you have Peter and Sydney hanging out which is a lot of fun.
Like I said before, its a movie that plays off the motifs of a romantic comedy but puts it in the setting of a bromance.
The focus of the movie isn't on these two but its passable and the two do have some fun chemistry. As stated before, Andy Samberg plays Peter's brother who is gay and is an expert on making friends. Simmons plays Peter's father, Jaime Pressley and Jon Favreau play a dysfunctional couple who do nothing but fight.
His character is funny because he says he gets bored with pursuing gay men and wants more of a challenge so he pursues straight men and actually succeeds. There's a couple other small performances that make this movie a lot of fun.
The thing that is appealing about this movie is that while it is a raunchy comedy, its not nearly as raunchy as something like Ted and could possibly appeal to a wider audience.
Again, its all a matter of taste, but I find this movie hilarious. As stated before, the relationship between Peter and Sydney is only made better by the performances of Paul Rudd and Jason Segel.
I Love You Man is the story of a young couple, Peter and Zooey (played by Paul Rudd and Rashida Jones).