They also rebox a lot of old kits from other manufacturers, including eastern european manufacturers, which I hear can be of variable quality - some dreadful, some rather good. Having said that, I've built a couple of the old Esci vehicles, reboxed as Italeri, and they were exceptionally good in design and fit, nary an issue to be found.
The only Italeri I've built other than the two vehicles was an Me210 which was good quality with a few fit issues and, yeah, the instructions were a little vague in places.