The user experience, though, is not great, and certainly not worth the effort it must have involved. Why reimplement draggable, modal windows? What does that get the user? Must we really duplicate all the worst excesses of GUI interfaces just because we can? There are some really brilliant moments here (e.g. the ability to add pictures directly from Google Image Search) where the designers clearly bothered to think about how exploit the strengths of web-app-ness, but a little more of that and a little less slavish devotion to the GUI paradigm would not have gone amiss; there's too much "look what we can do." Just because you can doesn't mean you should.

Also, the author of the linked post claims that it is responsive, which it certainly is not for me; it feels very, very sluggish, 1+ second delays for mouse clicks to register.