Story - We follow our main character after whom this series is named. A brutal, cold, highly skilled gunslinger who is in a word just badass and does badass things throughout the series, which for me atleat is pretty cool. Also, some of the story beats and plots are just so fun to witness. These unique plots are the things that set this manga far from being generic. So, if you like assassins, guns, badass characters and a nice unique plot then definitely give it a go. Art - Very detailed and good looking artwork. Specially the fight scenes! The battel on the ships, the trainscene all of them are just so cool. I would pay to watch some of the gun fight scenes in animation! I bet they'd look so ccol!

Overall -
A pretty nice and fun series! Worth giving a shot!