BlackBerry App World is a few months old and seems to be getting better as the weeks go by. The selection of apps is good, but still no themes to be found. There is a good listing of both Top Free and Top Paid apps, as well as categories to browse through. If you haven't checked it out yet, give it a shot. Check out the video for a run-through of all the features. If you missed it previously, you can also read this article on Getting Apps on your BlackBerry which gives an overview of different app store alternatives for BlackBerry along with some of the pros/cons to each.
It seems as though BlackBerry World started having some issues over the weekend and those still using BlackBerry 10 are currently unable to download apps. We've reached out to BlackBerry to inquire, they noted they're aware of the issue.
With BlackBerry moving to shut down BlackBerry World come December 31st, 2019, the BlackBerry World storefront team has already initiated some moves to make that process easier, but it means changes for developers and users!