I'm thinking of building a Restful app on either App engine or ec2 devloped in Java. I'm interested in opinions/experience of using the two options for this. The primary purpose is to create web services to write and retrieve data through a mobile device...basically creating an API for the service I want to create. It seems to me it would be quicker and cheaper in the beginning to go with google app engine using either restlet or grails.But I also think that I could run into problems in the future when I want to so somthing more advanced and might be restricted by app engines environment.

I also want to be able to do data analysis on the data in the datastore as well. It seems that with app engine this would be hard as I don't have direct access to the datastore ( in Amazon I could still have access to the underlying db if I go with MySQL ) .