EnterpriseDB (which started this project) specializes in providing postgresql version that can emulate most of Oracle database functionality, so this is not surprising.
No, it provides a basis to ease your migration from Oracle. There is a lot it doesn't do. Basically, if you have a homegrown app on Oracle it removes a lot of the low hanging fruit to migrate but you aren't running peoplesoft or something on it.
I personally never used it, but worked for a company who at the time used EDB to migrate away from Oracle. They apparently had a tons of stored procedures and they mostly worked, but it is possible they didn't use any of the things you mentioned.
Anyway maybe I should say differently, maybe they don't provide most of the functionality, but their goal is provide database that can help to migrate away from Oracle, and this storage engine that appears to mimic one in Oracle (and I'm guessing has similar tradeoffs) fits that model.