It's destructive criticism.

It can be quite amusing at times, but generally I avoid the blog as these things can ruin the enjoyment of just about anything, whether they're right or not.
As to what webcomics I read, way too much, especially before I deleted all the adresses from the bookmarks to see which I still will come back to eventually (a rather useful exercise, by the way; I heartily recommend if you're wasting more time than you have on webcomic habits).
Anyway, what I still have now on a regular basis:
- Sluggy Freelance;
- Doctor McNinja;
- Scary Go Round;
- Girl Genius;
- Otter Soldiers (a Finnish webcomic; rather hard to classify, but lets say that it's both extremelly surreal and has a coherent plot; also, the "elfs" are simply hilarious);
- The Broken Mirror (another Finnish webcomic, conspiciously enough... very different, though);
- Order of the Stick;
- Erfworld (on the same site, ofcourse);
- Nightmare World (at Golden Goat Studios; one word: horror).
And Penny Arcade, as of late.