I can't say anything about the consulting companies, but the developers in Walldorf that I got to know were all competent. I can only talk about my experiences and there are many in my social circle (computer science students at KIT) who are capable developers and either work for SAP as working students or would like to join SAP in the course of their professional life. As a first job, SAP is actually not that popular. But that's due to the fact that many don't want to join Big Corporate directly, but want to work at startups first.

Disclaimer: I am a working student at SAP