That is just the initial work to provide the basic infrastructure (and a solution to a couple of the simplest use cases) and not fully fledged materialized view

That is just the initial work to provide the basic infrastructure (and a solution to a couple of the simplest use cases) and not fully fledged materialized views. In 9.3 materialized views will only be refreshable by recomputing the entire view and they will be locked while they are being refreshed. To shorten the lock you would have to swap the view with ALTER MATERIALIZED VIEW.