I recently bought the first 15 volumes and enjoyed it tremendously. I'll agree, the humor is probably an acquired taste and a bit more difficult to appreciate due to the puns and parodies.. but it really gave me some hard laughs. The author is somewhat of a vulgar person, but I find him extremely funny.
I also love the art, the different personalities of the characters, as well as the already mentioned bizarre titles.

Definitely don't pass this up -- it's a great series.