Path and Facebook’s mobile left nav flyout pattern considered harmful?

Agreed. I've unfortunately already used them in a couple apps that had very nasty navigation requirements, and while it "works", it doesn't feel discoverable at all.

I went with actually showing the flyin navigation on app start, essentially making the flyin navigation the 'home page' for the app. I'd say just going with regular list or dashboard navigation would have been more intuitive, so I'll probably not use the pattern again in future...