I used GWT for a few years on two projects, but I would not use it on any future projects. The first was using GXT, which you should probably avoid for public facing sites.
We ran into some GWT compilation issues mainly due to code size a couple of times with some browsers, like Safari, that left us dead in the water until Google released an update.
The second project used vanilla GWT and we were very happy with how performant it was. But we avoided lots of GWT features which seem over-engineered and complicated. We used JSON overlay types instead of RPC calls (which made our compilation / or dev mode much faster - I forget honestly). We avoided MVP, because I never met anyone who actually fully understood MVP with GWT. Instead, we had a very simple MVC structure that worked great for us (but lacked unit tests..). We avoided most of the CSS features because the complexity/value wasn't favorable for us.
Moved on to a JS project afterwards and it was a breath of fresh air.
We ran into some GWT compilation issues mainly due to code size a couple of times with some browsers, like Safari, that left us dead in the water until Google released an update.
The second project used vanilla GWT and we were very happy with how performant it was. But we avoided lots of GWT features which seem over-engineered and complicated. We used JSON overlay types instead of RPC calls (which made our compilation / or dev mode much faster - I forget honestly). We avoided MVP, because I never met anyone who actually fully understood MVP with GWT. Instead, we had a very simple MVC structure that worked great for us (but lacked unit tests..). We avoided most of the CSS features because the complexity/value wasn't favorable for us.
Moved on to a JS project afterwards and it was a breath of fresh air.