On one hand, this is really great. It improves accessibility for blind users who depend on screen readers which are only capable of processing text.
But I think a lot of internet users don't realize the amount of information that is now routinely extracted from photographs. Facebook (and Google, Apple, Amazon, etc) can easily tell from your photographs if you have a pet dog, if you collect cameras, if you play golf, if you have children, or if you are just really into sunglasses. There's nothing stopping them from using this information to show you relevant ads just based on photos of you - even if another user uploaded the photo and didn't even directly tag you!
This is a very simple Chrome Extension that I hacked together in a few minutes to make it easy to see the tags that Facebook is automatically applying to you and your friends' photos. Once you install it, all the photos you see on your Facebook timeline will automatically be overlaid with their tags.
Super simple, super great idea.