The important question, only important question IMHO, is how they handle positives. Do they go all guns blazing and arrest the person on the spot? Or do they use a restrained approach and first nicely ask the person if they have any ID, etc? That's the important bit.
Match quality below 0.64 is automatically discarded >0.7 is considered reliable enough for an enquiry to be made.
So far ~1,035 arrests since last year resulting in 773 charges or cautions, which is pretty good when you consider that a 'trained' police officer's odds of correctly picking a stop and search candidate are 1 in 9.
In the UK you don't have to provide ID when asked, appropriate checks are made on arrest, and if you lied you get re-arrested for fraud.
The system has proved adept at monitoring sex offenders breaching their licence conditions - one man was caught with a 6-year-old when he was banned from being anywhere near children.
Before anyone waxes lyrical about the surveillance state and the number of CCTV cameras, me and the guy who stabbed me were caught on 40 cameras, and not a single one could ID either of us.