"Their native OS was no where near ready"
By that, I suppose you mean Meego.
I have recently used a N9 phone running Meego for a couple of hours and it was a real pleasure. In many regards it's better than Android has been until recently. It's snappy and looks well finished although look-wise there's work to make it compelling.
It's not really fair to give any real feedback on such a short utilization span but I wouldn't say the OS is "nowhere near ready".
Had they spent the same effort on Meego rather than on integrating the Windows OS, they would have a very, very good OS.
With Qt, they would also have very good technical fundation for developpers. Love or hate it, Qt programmers are very loyal to the library and praise it. With its ease of use, it could have been a developper-frendly platform.
I'd write a Qt app over a Dalvic-Java or Obj-C one anyday.
What I'd like to note on this story is that most tech writers feared that if Nokia didn't take this path, they would be shamed and welcomed their move. Now, given the sales both Microsoft and Nokia are shamed for taking this path.