One of the videos I saw on Engadget showed it working very well and very quick. I don't really care though... it's a cool feature but I never lock my phone.
If you start using Google Wallet you should lock it a few different ways. NFC is the next big thing. However, I don't see to many people venturing out without their wallet. I can just see going into a store and the NFC terminals are all down. Then what do you do. It'll 5 years before it takes off and that's only if someone else doesn't make a better product.