I've had really positive experiences with APEX. If you already have an Oracle DB, it's hard to beat for quickly standing up data centric business apps.
Disclaimer: APEX dev team member here. Independent of APEX and even the Oracle database, if you are not using stored procedures, you are not using the database efficiently. See e.g. this presentation for a performance analysis: https://www.youtube.com/watch?v=jfkph4lXmKU
Right, but it's not for developers. It's for users who would otherwise have knocked something together in Access. At least it gets them onto managed infrastructure rather than running it on their own PC for their workgroup...
The other is that nobody, if they can help it, uses ApEx.