It brought me a fair few luls, I learned things, I connected, I browsed gossip, and it wasn't so politically correct- which was just refreshing, even if I don't agree with the views some hold.
However, it was time consuming and had new content upon every new refresh, which to some is a benefit. The worst thing, however, was that I noticed I judged people more. The bitterness rubbed off on me. I would be more critical of people's clothes, words, of myself too.
Now I'm banned for a dumb reason, I seethe slightly, but I have the gift of retrospect, and can see that it was good to have some distance from that site. And they are obnoxious, the ban happy mods. Mods here are more lenient, but I guess it's smaller. And the users can be unpleasant on lolcow.
TL;DR, lolcow is great in moderated doses