OBWAT is definitely one of the Coen Brothers' best films.
The first time I saw it, I was sort of nonplussed but when I saw it again, I rolled with laughter. Today it is one of my faves of theirs.
Personally, I find it interesting because it takes place in rural Mississippi (in the 20's, I think) but those characters and their mannerisms are very, very familiar to me. Clooney looks slightly similar to one of my uncles.
Also, there is a shot of a newspaper at one point where they say that the dam is going up in Arkabutla. Arkabutla Lake (and Dam) are about 40 minutes south of my house. (It's also the birthplace of James Earl Jones.)
Great movie! (I love Pappy O'Daniel! "How we gonna run as the RE-form candidate when we're the god damned incumbent!?)