Nice try, Mozilla, but it’s too little, too late.
I waited for something like this for a long time, envying Opera users, and now that I have it in Firefox, I’m very disappointed.
The worst part is that there’s no way to add custom links or pages, as the layout only displays your most visited websites. You can remove or pin the sites that are automatically selected for you., but that’s it. Moreover, there are lots of duplicates (see bottom row in the picture).
Let’s see if Firefox 14, in 6 weeks, will improve this feature.