I too looked at Prestashop, but wasn't impressed in this area. their approach seem to be constructed from a programmers perspective and didn't really reflect the sort of real-world restrictions that people have asked me how to achieve over years.
As an example, Prestashop would allow you to decide whether a user can view, edit, add or delete a product (i.e. what access to they have to the functions in the product class), but the sort of thing I'm asked would be "how can I restrict my designers to see and edit only the products that they added?".
Of course, you couldn't do that now with 1.5. But you could create a new page that restricted designers to their own products and give them access to that rather than the existing product pages. The class access based approach wouldn't support this, as access is determined at a more fundamental level.
The data structure for the new admin access also supports moving pages to other menus and re-ordering the menus. It's pretty easy to do by dibbling in the database tables now, and I'd like to think that at some stage in the future there might even be a UI to allow it to be done from the Admin.