Several weeks ago Mary and I had a discussion at the Deep Dive at Local U about whether Google was using review sentiment in ranking. While I noted that the new patents for entity rank seemed to indicate that professional reviews might influence rank, that I had not seen any indication that sentiment as expressed within a review influenced ranking or that ranking for a good review corpus comparatively had a strong influence.
That all being said within Google restaurant search, Google is now autofiltering results based on phrases like good, best, cheapest etc. (As a note, while I just started noticing this recently it may have been present for quite some time).
The searches for things like “Best Restaurant NYC” works on both the desktop and mobile but the results are more obviously labeled in the mobile result. “Best” as a modifier returns only 4 star listings or better and “cheap” returns one $ sign listings. You can combine these modifier words and see results for Best Cheap Restaurant NYC:
Google Local Restaurant Search Autofilters on Best, Cheapest Like Phrases by Mike Blumenthal