EXT-GWT Question:

Problems with indexing by search engines - IMHO, this should be the biggest disadvantage of using GWT, or pure JS web applications in general. Since the content, layout, everything is created \"on-the-fly\" with JS, the search engine will only see a very short HTML page and that\'s that - you have to take care of this somehow yourself (for example, using cloaking). Google has finally started to work on a solution for this, however it doesn\'t seem to attractive to me.
Update: Google has finally addressed this problem. However, I\'ll leave this as a trade-off because making the application crawable still requires more effort than in other frameworks. At least now we have a \"standard\" to follow and don\'t have to use some dubious techniques (like cloaking).

Need lot of memory to run it in dev mode.
High compile time.
Every server call will be ajax.
You will loose control on your javascript.