YouTube works great on the iPhone, but it seems to be not as easy to use through their mobile site (m.youtube.com) when using Windows Mobile phones. However there is now an app you can download for WinMo on the Mobile YouTube site and supposedly it is supposed to be a lot faster now.
While making the app faster, YouTube has been able to increase the quality of the videos. Below is a video demo of the new app in use. Other features that have been improved on the new YouTube mobile application is easier video viewing, improved WiFi streaming, and support for more mobile devices.