Story: A business man gets taken in by a delivery crew sounds like a boring plot, but not in Black Lagoon. There is so much action in this show that it is unrivaled. A great part about this show is that it is believable for the most part (definitely pushes reality but in a good way). If you want in your face action every episode, then this is for you.
Animation: The animation is really good in this show. I love how the action scenes are played out and how they are displayed. Getting a lot of action really quickly usually means cutting from screenshot to screenshot. But in Black Lagoon I am always aware of what is going on at all times.
Sound: I really like the sound. The dub is really good, and the sub is pretty good too. The gunshots, the voices, the explosions, and just about everything sounds good to me.
Characters: The characters in this show are so diverse. Black, white, asian, you name and they got it. Each character has a unique background and it shows through their actions. I do not dislike anyone in this show, and that is rare for me. Revy is especially... AWESOME. She makes the show what it is. Her troubled past is evident and sad, her actions are understanable, and her ability to kick ass is definitly kick ass. I love Revy as a character, she may be my favorite character of all time.
Overall: This show is so cool. I obsessed over it for the longest time. Going back and watching it never gets old. The only knock I have against the show is that it is so short. Many questions are raised in this show and the sequels but the show did not continue. I would love for this show to come back, I do not know why is doesn't. Overall though, YOU GOTTA WATCH THIS SHOW.