I haven't used WP7, so don't know if it works well.
I hope it is good. More good software and products is always a win for consumers.

I think brand loyalty is somewhat overrated.
When the first Nokia WP device is released, I doubt if it will be cheap.
But the current WP7 devices are becoming very affordable, the LG and Samsung are 200-250 euros (without a contract). So if you are interested in WP7, buying one of those would probably be a better idea.
And if WP turns out to be not for you, you can buy the MeeGo/Harmattan or an Android/iphone device in 6-12 months