Well, I had no trouble dragging them...sometimes. Other times, the page thought I was trying to drag the whole screen around. And sometimes drop worked and sometimes it didn't. They seem to have their very own (unspecified) rule about where a tile can go.
I would sure never want to use that interface, as it is now, in any commercial site!!
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.