After opening the lid, it pretty instantly shows the password dialog box, but that UI is a lie. In reality, what is immediately shown is a screenshot of what the screen looked like when it went to sleep. The UI, although visible, is not functional for almost 10 seconds. You can most easily tell that this is happening by watching the clock display in the upper right of the display. Right after opening the lid, it will show the incorrect time (the time when the laptop went to sleep). After 8-10 seconds, the time will become accurate and this is the signal that you can actually start typing your password to unlock the laptop.
What is actually happening is that these new MacBook Pro’s (and recent MacBook Air’s) have a new powersaving mode which Apple calls standby. Standby mode kicks in after the laptop has been in normal sleep mode for about an hour. When that happens, the contents of RAM are written to the hard drive and the RAM is powered down to further extend battery life. In theory, the laptop will last up to 30 days in standby mode. The trade off is that, when waking up, it takes a long time to reload 16 GB of RAM from the hard drive (even with SSD).
This has been bothering me for a while now and using the simple Terminal command to change the default standby time from 1 hour to any other longer duration works a treat.