This is pretty amazing -- they gave me Skype-based demo when I was being briefed -- much like the YouTube video above -- it's amazing to see someone tap on an application like Facebook and the application "looks at you" and recognizes you and grants you immediate access.
And the higher security stuff that also requires voice identification -- and that works even in noisy environments -- is really rather clever.
One interesting concept of security and especially for crypto systems is Shamir's Law which states that security / cryptography is not broken / cracked but bypassed and there are many examples of this holding true.
I think most users will find the convenience vs. security trade-off a worthwhile one. True, a combination of facial recognition plus voice recognition is not completely secure, but neither is the 4-digit PIN if someone looks over your shoulder while you enter it. The number of times per day the average smartphone user needs to do this is enough to become annoying, so a faster method that has "good enough" security will be a welcome improvement.
There was a recent story about the voice control on the Xbox One that is a good reminder about potential problems with this security paradigm. The latest commercial has an actor bringing up his box with the "Xbox on" command. The problem is that apparently Xbox Ones were turning themselves on when hearing the commercial. A video of a user saying the password might just do the same here. One possibility might be to have the tablet ask a simple question as a secondary check. That would make a recorded crack harder.
@Adam-Taylor: "security / cryptography is not broken / cracked but bypassed"
About 10 days ago I assisted to a conference and round-table hosted by Telefonica/Movistar (the biggest Spanish telecom provider) about enterprise-level security in information technologies and this was stated and exemplifed by most of the VIP attendants, including a world-class hacker, the boss of security systems at Telefonica and the Navarra Autonomous Police chief officer.
I got really scared when I heard how easy an "unbreakable" system can by bypassed by skilled hackers.
I forgot to mention in this column that a simple photo of the person won't work -- the system is also looking for little muscle twitches and eye blinks and suchlike to know that it's looking as a living person.