I am often in Oberammergau as a quick detour on my way elsewhere. The Red Riding Hood House and the Hänsel und Gretel home are worth some photographs, although I do feel intrusive of the familiy at the Red Riding Hood house as I usually see them eating breakfast. To live in such a famous house must get tiresome!

I am usually on my way for a walk on the grounds of Linderhof, which I would recommend any time over the far too touristy Neuschwanstein.

As a side trip as part of a larger visit to the area I recommend it. But there are also some very touristy things like the Käthe Wohlfahrt shop (although I do like the Konditorei across the road from there)

For the Passion Play? No, unless that is some sort of pilgramage that you feel you must make in life. Better to stop at Ettal and have a chat with the brothers there - they enjoy meeting visitors even if not of the same faith.