I've been experimenting with ROO for a few weeks now and based on that experience here are the broad things I would like to see added to ROO:
(This is not to say that ROO isn't awesome. It is awesome. Well done.)
1. Support for setting order on collections and queries. Need a) support for lists (which can maintain arbitrarily ordered data) instead of just sets in domain objects, and b) some sort of "order by" option on entities, collection properties and finders. Of course we can implement comparable, but in many cases we want the db to order the result sets before returning them, and once we get them we want to keep them in the order the db gave them.
(The "order by' on finders feature may be addressed here: http://jira.springframework.org/browse/ROO-241.)
2. Stronger support for the common "user-driven" application archetype that relies heavily on relationships to a user account. To achieve this now, the controller methods have to be modified to obtain the user's id, and the entity methods have to be modified to pass the user's id in queries of associated objects. I expect to have to customize and maintain the forms, but it would be nice if Roo could manage the controllers and entities in such a typical case.
It may not be feasible to do this kind of "archetype" support, but maybe some sort of extension that allows: a) a reference to the logged-in user to be added to each persistence method and b) the ability to add where and order clauses to the query (including with references to the user object). (Of course this might be easier if Roo also generated the user object as part of its Spring Security integration.)
3. Ability to access my entire roo command history for a project. Helps to create scripts or just remind myself what steps were taken.
Hope those make sense. (#2 is hard to explain, but I think you'd run into several issues if you tried developing any heavily user-driven application such as a personal music library or something like that where virtually all of the objects persisted are related to a user account.)
My two cents. Overall, this has been a nice experience.