This is a lose-lose situation.
Microsoft always had Nokia to rely on to keep making awesome phones and also the upcoming Nokia Tablets. Was there any indication that Nokia would stop making making new devices for windows ? No. Why did Microsoft just lose cold hard cash ? I don't know.
From Nokia's side, this is even worse. They may have gotten immediate cash but lost all *control* to move innovations on their *own* terms. Nokia figured out the main competency and marketing schtick ..which is centered around camera. Microsoft might have thought how windows phone should look like with it's surface phone idea....but clearly Nokia figured out something else. Nokia seriously lost this because they could have as well put Android on their awesome phones. It's always good to have options. What's the point of losing options ?