[breathesalt]

GWT has quite a learning curve. I'm 5 months into GWT/GAE, not counting preliminary research/learning, and am only now starting to see a return on my time investment. Looking back, I'm glad I decided to roll my own small framework for GWT/GAE; everything else just seemed inflexible, overkill, and too proprietary. I recommend taking a look at http://www.gwtapps.com/ which has been very helpful through my journey, even if it's somewhat dated.

There's practically zero support for Maven in the GWT documentation, and it's a shame because it seems much more elegant than just Ant. Ant is probably what I hate most about GWT, but beyond the initial setup, I haven't dealt with it much other than simply running "ant build" and "ant devmode".

My honest advice is unless you really like working with Java or are already past the learning curve, just go the HTML5, Backbone.js, Bootstrap/LESS, and Coffeescript route. GWT's worth the investment but the web standards it's built on will still leak through on sufficiently complex projects. Also, I couldn't see myself doing GWT if I wasn't also doing Java GAE, because GWT-RPC makes AJAX so painless.