Even with its new design, I find it surprisingly primitive. I don't have an account, but if i try to watch a set from some user as a slideshow, I have no option to scale the picture to my screen size (or at least no obvious way of doing it). Furthermore, when I rightclick, I get a list of sizes, but those links only embed a full-size picture into a new page. How useful is that.

Anyway, needs lots of improvements.

On an unrelated note, I am planning to make a backup of all my ebooks there, by storing them as pictures (something like https://github.com/meltingice/flickr-store, but better).