Yasr 1.2.1 will be an important update for Rich Snippets. Google announced that finally json-ld is fully supported for reviews. In fact, this guide has been updated and now it doesn’t says anymore that json-ld has to be implemented.
Yasr 1.2.1 should be released in the next week.
UPDATE: Due to this bug the new rich snippet system will be released on version 1.2.2.