Even though you can pin contacts to the home screen there is a huge difference since the contact tile isn?t updated with message counter, latest update from contact etc as it was on 8.1.
In addition contact details does not contain log history across various services such as mail, call history, facebook, linkedin etc.
Only text message log is available.
So to get an overview of communication with a contact you now need to open X number of apps instead of having it all on the live tile.
And to me, that is a big stepback, since this was one of the things that really differentiated WP from IOS and Android.
Loosing functionality when upgrading can be hard to accept (and understand).