I am interested in the possibility that GWT could serve as the basis for my entire presentation layer.
I would be interested to know if anyone has tried this successful
We have done this for a very large project, and as long as you know it's limitations, strengths and weaknesses it works great. Funnily enough presentation was the least of our hassles, as we just skinned it just like you would any other HTML page, using CSS. The project went live, and ran flawlessly so I have no complaints.
The pitfalls I found with it you can find here:
Biggest GWT Pitfalls?