Could be argued as one of the contenders for best anime ever, it was one of the first I started with.
The art style feels older but it works for the western motif the show has going for it. I also wasn't amazed by the soundtrack. The music fit the setting, but I never really wanted to hear anything again... which was too bad because that show loves repeating itself music-wise.
However, the story starts off somewhat simple and slowly builds on itself. The characters are likable and the villains are fascinating (particularly Legato).
This review is probably pointless though... pretty much everyone has seen this thing or plans on seeing it... and good for them.