So, one thing I really like about this is there's no UI clutter - just an editor and a footer. That would make this sort of thing great for embedding into another app. Another thing I like is you can create a new document simply by navigating to a random URL. Again, great for embedding (where the containing app can just name files after a UUID or whatever).

The down side is I typed some stuff, then clicked reload and my text was a bit scrambled. So I'm going to say your operational transform implementation is a bit buggy :)