I think people are being excessively negative towards Anderson, many of whom I imagine have barely seen him. He's still developing yes, but he has many excellent qualities. He is a goal threat, can create, and is rapid. Contrary to generalisation of lazy Brazilians, he can also work hard too.
I agree that he is not a graceful dribbler in the Eden Hazard level, but then neither is Gareth Bale. Personally, I think the deal could certainly turn out disastrously, but I also think he could just as well have a Gareth Bale type impact too, as I see them as very similar players. Both are rapid and powerful, both have a great strike on them too. Anderson is not British and may not adapt, Bale has four more years on him and will cost nearly 3x as much.
Anderson will probably go to Bayern if not us, and his thread will become very interesting in the year or two after that.