we have several successful scenario/projects with adf  11g in more than 3 big enterprise in Iran there is no problem with farsi but you need to buy some persian  component and standard from companies that has developed them.such as the farsi version of the af:inputdate... or the farsi version of all english word used in component such as "view" in af:table...
at the moment one of your system has more than 800 users and it is performing really good  it is totally developed with adf 11g and we spend about 5-6 mellion tomans regarding the buying of the library/persian/standards.

I am had a good  experience from use Oracle ADF 11g.
It has very comfortable and useful Component that we can use in our web application,but there is a problem,this components have many problem in browsers such as IE7 and upper
,FireFox and opera and the problems are different in each browsers.
So,I You want to have and hi performance application  with pretty good Component i suggest to ADF 11g,if you cant solve the problem.