The original series seemed to be one of those love/hate shows, you either loved it or hated it. If you did enjoy the first series you should like the second BUT they have changed quite a few things.
If you're a sub fan then almost all the VAs are different in Il Teatrino. The character design has also been changed somewhat.
The basic background to the story is unchanged, the girls (cybernetically enhanced after being rescued from 'fatal' accidents or terminal illnesses) and their handlers (usually retired police or army with a good few screws missing) fighting a covert war against the mafia. Nothing new there Il Teatrino does delve more into the background of some of the mafia characters, which makes a nice change. Less time is spent on the relationships between the girls and their handlers. This was the focus of the first series.
The first series mostly revolved around Henrietta and her handler Jose (or Guise depending on the subs). Il Teatrino doesn't have a single main character as such but rather spends time on almost all of the main players on both sides of the story.
There is a main story to hold the series together but its not that complex and doesn't go very far. But then its not really the most important bit of the series.
Budget has suffered for Il Teatrino, the animation is not as good as the original. It still looks good but the fight scenes are a bit poor and there is much use of static and panning shots to fill time.
I give Gunslinger Girl - Il Teatrino 4 kitties:
I'd love to see the whole manga series translated. Its in the hands of ADV so no hope there....