I just switched to a WP (Titan II) last week. It may be new phone smell but I really like it. I wasn't a heavy app user though.

In showing the phone to my family/friends the biggest confusion I have found was the People pane. They thought in terms of the Facebook app and the Twitter app. Once I explained that those apps are all 'in' the people pane and linked to their phone profile things went smoothly. Overall I felt they really liked the look of the phone.

Personally I like the social media integration and the tile interface look. Rather than a feeling of reaching out to Twitter or Facebook those things are delivered to me. I don't have Joe on Facebook and Joe on Twitter, etc. I just have Joe and all his updates are delivered and grouped together in a nice way.