I've mentioned this before else where, but Dubai doesn't need this because crime is so low compared to most countries that the only reason it may be used is solely for publicity. In majority parts of the city, you can still walk around at night and not be as worried as you would in other cities.

Hence, it makes me want to throw out the idea of how effective this facial recognition really is. If your sole reason is marketing, you won't care much for effective use of said tech.