Theoretically their router should prepend the hash fragment to the URL, but it gets stuck in a redirect loop and hangs the browser. The workarounds I've found so far are to use hash style URLs or not use a default route, neither of which are optimal. (Edit: updating to 1.0.1 fixes the problem as long as your "otherwise" route is a defined route)

Version 1.0 (they are currently on 1.0.1) of the framework broke their website for IE users, which makes me a little nervous about the level of cross-browser testing that the framework uses. Their documentation is sparse in some areas, which is an annoyance more than anything (the source is fine to read, but be forewarned that it's not a small project by any stretch of the imagination).

On the plus side, not having to litter ko.observable everywhere was nice, their concept of services (for working with REST endpoints) is great, and it's been pretty easy to break everything up into maintainable modules.