- In the rewrite of Interactive Reports, the IR component was completely revamped from top to bottom. The markup used for IRs in APEX 5 is dramatically improved: less tables, much smaller and more efficient markup, better accessibility, etc. However, if you've also followed this blog post from Shakeeb Rahman (@shakeeb) from 2010, and directly overrode the CSS classes used in Interactive Reports, that will no longer work in IRs in APEX 5. Your custom styling by using these classes will not have any effect.
- As the Oracle Application Express 5 Beta documentation enumerates, there is a modest list of deprecated features and a very small list of features which are no longer supported. "Deprecated" means "will still work in APEX 5, but will go away in a future release of APEX, most likely the next major release of APEX". In some cases, like the deprecated page attributes for example, if you have existing applications that use these attributes, they will still function as in earlier releases of APEX, but you won't have the ability to set it for new pages. Personally, I'm most eager to get rid of all uses of APEX_PLSQL_JOB - customers should use SYS.DBMS_SCHEDULER - it's far richer in functionality.
Please understand that we have carefully considered all of these decisions - even labored for days, in some cases. And while some of these changes could be disruptive for existing customers, especially if you've used something that is internal and not documented, we would rather have the APEX Community be made aware of these changes up front, rather than be silent about it and hope for the best.