One of my favorite animes of all time. It lasted 74 episodes and was amazing. It stayed close to the manga as well from what I have heard.
I haven't finished the series (I had to stop from lack of time and then took up other anime), but I can definitely say the first 40 episodes were great.
If you have not seen it, I recommend watching it all.
The first few episodes take awhile to pick up... but after the third episode or so, it gets very intense and stays that way.