Windows Phone has been accused of missing many big name apps despite many and often better 3rd party apps.
Pinterest is just such and app and again despite some fantastic 3rd party efforts people want official.
Sadly for Windows Phone users this official app which is classed as a beta is nothing more than a home style wrapper app. This means that while everything should work fairly well you will not enjoy the same level of integration or performance as Android or its users.
If you would like to try Pinterest download it here