Expanded thoughts (contain spoilers):
The Comedy reminded me of Bret Easton Ellis' novel Less Than Zero, which, on the surface, is a series of loosely connected, seemingly pointless vignettes about shallow, amoral college kids partying in LA. It's highly polarizing, and happens to be one of my favorite books of all time. There's a deep poignancy to it that doesn't translate into words very well; I just felt that I knew what Ellis was getting at, and was moved by what happened to his characters. It's a subtle yet devastating novel, but it doesn't have elements that appeal to everyone. It speaks to you, or it doesn't; that kind of thing.
I can't identify with any characters in The Comedy like I could in LTZ, but once I picked up on its tone I began watching it as if it were a similar type of work, just in a different setting with different types of people. And I thought it worked pretty well. I thought the main character did evolve and was able to find a new dimension of humanity in himself. For instance, in the scene where he wanders into the dying guy's hospital room - after playing with his hair, his eyes wander to the photos of the kids on the wall (old guy's grandkids I guess?) and he studies them. Then the girl nurse walks in, surprising him, thinking he was the old guy's son, and he began to play it off like he was. This is where I expected him to be an asshole and troll her, and his eyes dart over to her and it looked like he was about to say something, but he shuts up. It's subtle, of course, but I don't think there's any doubt he would've acted differently in the first half of the film. Then he's able to form a connection with the girl he works with, which I don't think could've happened with his character in the first half either.
The subtlety of the above examples (which I could've read into completely wrong, for all I know) are a result of Tim Heidecker's acting, which I really thought was outstanding. Apparently the script was largely improvisational, and I thought most of it was handled really well. This fact further increased my respect for the film. The dialogue sounded genuine, like it was how real (often drunk) people sound, and managed to be quite funny. Maybe the script was best suited for professional comedians, who make up a lot of the cast.
I get why a lot of people wouldn't like it, and had I not connected it with a favorite book of mine, I probably wouldn't have liked it either. But it's now stuck in my mind, and if nothing else, I respect it for making me reflect on it.
4 out of 5 stars - and a good first choice, in terms of bringing out a lot of different opinions.