Oracle Application Express or Oracle Apex or formerly called HTML DB is the same, various names to define the same product, been around 2002 and part of oracle database installations since 2004.
With Oracle database benefits on back end, try build the web generation, the origins are replace MS access. The developers not need adicional information or learn tons of documentation or other degree to start build with Oracle Apex. We find APEX to be a great tool for rapid development and maintenance of efficient, responsive and scalable applications.
The security, Oracle apex have numerous features out-of-the-box, easily can authenticate over LDAP, Oracle Single-signon, Oracle Database credentials, or HTTP Header variable.
The best think of apex is "Built in Apex to Deploy Apex", and is true, developers not need anything more
The cost is the best, capitalize database investment, amazing solution at very low price or even free with oracle XE database.
Installation complexity is the worst. The conversion rate is very high when new developers join.
The web networks standards not meet in APEX.