APEX 5.0 Universal theme migration guide
Migrating your 4.x Oracle APEX applications to new version? How?
White paper has been released
Just a useful thing to note is that Oracle announced a migration guide on how to get all of your current APEX 4.x themes upgraded to latest version and Universal theme.
More details can be found on Universal Theme migration guide
As mentioned in the guide you should not have issues with the business logic transferred but only with look an feel and ability of clients to get used to new look and feel. Obviously we would still need to verify this and it will be interesting to see if this really is going to work as expected. Fingers crossed and look forward to new migration challenges.
Few days before I noticed a blog from Denes where he is already noticing few issues but it could be related to certain Windows OS configuration so will leave a benefit of a doubt. :)
Original post can be found here.
Thanks again APEX team.