Gunslinger girl is a good anime overall; however, it has its flaws. As well as having amazing animation and having a really great story. It is awefully slow. Nevertheless, i still watched the anime and ended up liking it a lot. You just need the mind to sit through it.
However, in this anime i found that you had to concentrate. Im not sure if that was just me or if i was tired
. The structure of the anime is amazing. Everytime it reveals something, or has a flashback your just like "Wow.."
Overall, this anime is good. But if your into fast paced animes with loads of battles and fightscenes maybe you should look somewhere else. For this anime if not for children.