An issue I seem to have ran into (with FF) was browsing later pages (page 7 for example) and then trying to hide official/built in addons by clicking the check box in the left column and "Update".
I was expecting to see only "third-part" addons, but instead, no addon at all was displayed.
I reset the page by clicking the Addon tab on top and went again for the checkboxes and "Update". On the first page, it displayed the third-part addons only, as expected.
Otherwise, seems to work pretty good so far.
I'm looking forward to see addons authors put more content in those.