Well my Android phone came with an email application besides Googlemail. But it could be slow loading mail at times so I tried out K9. And still use it. But changed the icon on the phone to something more acceptable to me.
I don't use the provided Samsung Galaxy S launcher. But seconds to swap back.
The Samsung one is good and iPhone like but there is more scope to customise. I currently use the ADW Launcher. It is possible to even get 5 rows x 5 columns of icons....