Yes, it's taken like 2-3 solid years of recommendations, and the worst new television season in a long fucking time, but I've finally given It's Always Sunny a shot. There was nothing else to watch due to the awful new TV series, I got the DVDs cheap, and hey, a half hour show is easier to watch than an hour.
The first episode left a strong first impression, and I am sure it gets better from here, because that's how pilots work. It was clearly heavily influenced by Seinfeld (because it has the group dynamic) and CYE (because it's more assholish and mean than Seinfeld), but I'd like to say that I think there might be a Coupling influence, too. In particular, the show is not afraid to make the characters really, really dumb, far dumber than they normally are, far too dumb for believability, in order to make a gag, sometimes even a single scene gag, work. While this is not a bad trait (one of the great parts of being a writer is that you can make your characters as stupid as you'd like to suit your own needs), there were one or two times in the first episode where the characters were made, well, too dumb. There is a line. But again, this is the first episode and I am sure they were testing the waters with many elements, and the bits I am talking about are fairly obvious sore thumbs. I'm not even worried about this.
The only thing that truly worries me. . .is Danny Devito in season 2. He can be a very funny man, but between his lack of visibility in recent years, and the already fairly tight ensemble, well, he's THE WILDCARD here.