I've been a fan for many years and quite like the majority of their work. That being said, I'll agree Thom Yorke can be quite annoying when hes doing anything other than playing music. I went to a show once in Vancouver and the fucker broke out into political/save the environment speech.
That being said, musically, they can be quite good. Even Brad Mehldau agrees, having done his own renditions of a number of Radiohead tracks. Not going to appeal to authority, but c'mon, the man is one of the best Jazz pianists breathing, the guy knows music. Here's Brand Mehldau playing one of my favorite Radiohead tracks, "Knives out".