Actually, MS is the winner here, not Nokia - I still don't get how Nokia could agree to that deal...
MS managed to get a handset manufacturer with an excellent reputation and loyal customer base (in Europe and the developing world that is). Nokia handsets are virtually a synonym for sturdy and well built. Plus, acquiring the Ovi Store and Ovi maps instantly turns the weak map app made by MS into a worthy competitor for Android's Google Maps and vastly increases the number of software for MS. Plus, the Nokia brand is very well known with general consumers while WP7 is something most have never heard of.
Nokia on the other hand busted its chances to release an Android phone and restore their presence in the smartphone market. WP7 is good and I don't doubt it will find a loyal customer base, but it was late to the game, has poor hardware support and lacks the vast dev community iOS and Android have behind them.