After I updated my phone, I was excited to try out the double-tap unlock but it didn't happen - only to realise it isn't there for the 620. Same like you guys, when I went into the touch settings there was a real quick flick of the options for double-tap unlock. The thing does exist in the phone somewhere. Now I really hope Nokia will enable it for the 620..
Its same in Lumia520 and i have tried to activate it but its super fast
hope we get that update in bittersweet shimmer ������