No it's not
>> This system's not perfect. In fact it's pretty poor but still better than nothing.
No it's not, you are misunderstanding what has been said, however you do need the full set of figures to really understand what has been done.
If it has 'matched' 100 people and it has a false positive rate of 98% then 98 of those matches are wrong, No if's, no but's. That is rubbish, it's not better than nothing as you've wasted time on 98 people who you think are a match because the computer goes ping. It's not just the 98 people, its all the police time that's been wasted as well.
We need to know the False Negative Rate as that is NOT simply the reverse of the FPR. It could well be that the FNR failed to identify 98% of the people it should have done. You would be better off sticking a pin in a photograph and arresting that person.
The last time I looked at this technology was about 10 years ago and we were getting a fraction under 80% recognition rate on reasonable quality passport sized photos of adults between 18 and 65. Pointless doing it on kids unless the photo is very recent and even then, not good. Often pointless on older people as their face sags with old age making the face detection tricky.
I'm a little surprised that the Met is getting such rubbish results as technology has moved on a lot. I suspect that they paid peanuts and got monkey technology. However thats just a guess.