Hardware is decent. Better responsiveness on their lower end hardware than Android on better, more expensive hardware. Still find iPhone tighter.
Development is not the pain/mess it is on Android. (See Android NDK for real pain.) However, Microsoft makes it arbitrarily painful to develop because they still refuse to support/conform APIs and protocols found on _every_ other platform from desktop to mobile, such as OpenGL (ANGLE doesn't count) and OpenAL for games, to Zeroconf (aka Bonjour on Apple platforms, but compatible implementations are found everywhere but from Microsoft and WinRT). Their C compiler still officially hasn't moved beyond C89 which is 2 standards out of date and particularly important for a lot of cross-platform open source native projects. (They've recently fixed it so they can at least compile Git, but refuse to make an honest attempt to make their compiler compliant to C99/C11.) And they arbitrarily broke compatibility with a lot of their Windows APIs making sure they alienate both developers from other platforms as well as those already in the Windows ecosystem.
Recent market analysis shows their marketshare is shrinking...around 2% worldwide. (Because the number of iOS and Android increases, not because they are losing customers.)
So just from marketshare numbers, I don't expect things to get substantially better than Microsoft even though I think their phone may be better than the Android counterparts. (Microsoft's culture is better suited for competing with Google, but in their current position, their best features in the phone make them compete with Apple which isn't going to end well if you remember their history, like Zune.)
And because development for WinRT is painful enough, most developers aren't going to bother for such a minor marketshare. (And monetization in the Windows Store is not much better than Android in aggregate...which means it is bad. Nowhere close to iOS.)
Android+iOS already gives developers what they are looking for. Android has mass marketshare. iOS has monetization and the ability to make apps that 'wow' people.
So if you want to buy a phone and just want the phone, go for it as it isn't that bad of a phone. But don't expect the marketplace or ecosystem to go along with you.