I think this is poor design choice. Why would you want to "unlock" a laptop. It is not prone to accidental touches when it's in your pocket or the bag, which is exactly what "<gesture> to unlock" is supposed to prevent.
Now, I'm worried that they've done this just to look cool and so that people go "hey, I do that on my Windows PC, and the same gesture works on my (very rarely found) Windows phone".
They've always had this. Previously it's been called "Ctrl+Alt+Del Unlock". It then takes you to the password prompt. This is just replacing that key combination with a prettier screen, and also adding a quick glance at how many emails you've received, how many IM chats, weather forecast, etc without having to log in.
Without getting into the discussion on how incredibly important a password on a laptop is, you can disable this lock screen just like you would disable the password prompt after coming back from sleep mode on any previous version of Windows.
Again, you don't have to slide to unlock. You can just press a keyboard key. And it's always been there.
Wasn't the point of having C+A+D to get Windows' attention, thereby assuring that only a valid login window will receive your login credentials? How does this handle that?
It's not like they can't detect if your computer is equipped with touch or not.