I've done GWT for about 2.5 years from version 1.x to 2.x. I'm not sure I prefer one or the other.
GWT development is a bit painful to setup and to work day-to-day.
It's nice to have the similar Java structure and to be able to write unit-tests to test the app via MVP patterns but I'm still not sure it's a big win for me going forward. Especially when the founding members have left the team.
Knowing Javascript, GWT is a win.