(edited response)
You wrote : I have copiedlibs\social\reviews\components\hbs\reviews\review.review.hbs to apps/myProject/components/social/reviews/hbs/reviews/review.hbs
1) To overlay, you must use an identical path, making use of the fact that, if the resource property does not contain an absolute path, then /apps is searched before /libs. Thus, to truly Overly, you must create /apps/social/reviews/components/hbs folder to contain a reviews component.
2) Reviews is a combination of Comments and Tally. If you're overlaying the commenting feature, then you need to overlay the comment system in a manner similar to the Overlay tutorial. Which means you need both
/apps/social/reviews/components/hbs/reviews
/apps/social/reviews/components/hbs/reviews/review
The review.hbs script should exist in /apps/social/reviews/components/hbs/reviews/review folder (same as in /libs).
3) You need to set the properties appropriately on the overlaid reviews component.
/apps/social/reviews/components/hbs/reviews
sling:resourceSuperType String social/commons/components/hbs/comments
sling:resourceType String social/reviews/components/hbs/reviews
/apps/social/reviews/components/hbs/reviews/review
sling:resourceSuperType String social/commons/components/hbs/comments/comment
sling:resourceType String social/reviews/components/hbs/reviews/review
Then copy /libs/social/reviews/components/hbs/reviews/review/review.hbs into /apps at the same location and now you should be able to see your edits.
- JK
Note : there are some updates being made to the samples, so I recommend using the English version of the documentation until the German version catches up, e.g.
http://docs.adobe.com/docs/en/aem/6-0/develop/social-communities/essentials/rating.html