599
Microsoft CEO Satya Nadella admits giving up on Windows Phone and mobile was a mistake
(www.theverge.com)
This is a most excellent place for technology news and articles.
If you're talking about WinCE/Pocket, etc, it was an extremely bad UI paradigm for a phone and a button free design in this case made it worse, not better and no one copied that especially not after the iPhone was announced and shown.
The last iteration of Windows Phone (eg: Metro) was actually quite good, but wouldn't have existed without iPhone/Android before it. It being more like iPhone wasn't what hurt it, what hurt it was that they never got the dev support needed. My wife had a Windows phone for around a year, and the thing that ultimately moved her to iPhone wasn't that she didn't like the phone, it was that she was constantly left out of things because it was probably more rare for an app to hit Windows Phone than Linux.
Microsoft did have the right idea with getting to mobile/tablets before most, but MS has never really had good taste when it comes to software UI.