It all depends how the kid is brought up. McDonalds is a treat and they should get a toy. It shouldn't be seen as a place where you get books. Equating junk food and reading isn't great is it?

The books will be taken home
they will not read it there

It's a nice idea, as said as a treat they are fine it's when they are eaten regularly it's a problem.
My 2 are teenagers and still see having takeout as a 'treat' :)

I think this is a good idea, it might encourage family-child reading which that bond can be lost in a busy society.