There's nothing wrong with optimising for Grandma. The key is to make the most useful features easy to get at, and the more powerful ones discoverable.
The bookmark/history manager could be better. It has no autocomplete/awesomeness in the search. It's actually quite an awkward UI.
It's not keyboard friendly. And their are odd inconsistancies. Should the default behaviour of clicking on a link open it in new tab?
Recent bookmarks and most visited are nice smart bookmark folder, these are useful but hard to reach in that tool. Some bookmark management feels a little like a black box.
At least you can tag bookmarks. Scrolling through a massive list of tags isn't much fun.