Q. Is quantity or quality better when it comes to Google Places reviews?
A. It appears at the moment the more reviews you have and the greater the number of review sources you have the better your Google map will rank in the search results. Even negative reviews can increase a maps ranking.
To get more review sources simply sign up to review sites Google scrapes reviews from. These can be found easily by looking at the highest ranking place pages in your business area.
From a user perspective and click through rate it is obviously better to have quality positive reviews that will help convert potential customers.
So to answer the question it is better to have a large number of descriptive and positive reviews. Try and entice happy customers to leave a positive review on your Google Places listing.