I really enjoyed it, thought it was absolutely fantastic. The theme or mood of the whole story definitely shifts from the beginning; it lost its dark and horrific feel later in the story. However, watching it convinced me to go pick up the manga and wait excitedly for the next season.
Confession time. Haven't read the manga (Can't do the style. Something about the way that I read, I struggle with graphic novels of any description) but I have read most of the wiki, so I have the gist of what's going on later in the series, and I CANNOT WAIT for the anime. Also if you've never watched it before, enjoy Cowboy Bebop. Seriously one of those things I wish I could completely forget so I could watch it fresh again.
Make sure to listen to the soundtrack too Or at least the intro.