In my experience, "ordinary users" have either poor eyesight or poor literacy, because they read impossibly slow and are unable to process an entire screen full of data. If they have a dialog open and you ask them to click a specific checkbox, they will be unable to find it, taking a minute or two of moving the mouse in random directions while I tell them whether they are hot or cold.
I've never met a user who (a) would need help discovering a new interface, and (b) could read the entire screen, while (c) simultaneously reading my facial cues for hints.
For this reason, I'd expect Gnome 3 to be more discoverable, since it clears away everything except the stuff relevant to what you're trying to do.
This is certainly how I feel about it -- I have used a tiling WM for years, so most all user interfaces feel foreign and confusing to me. But when I use others' computers, I find Gnome 3 to be very "intuitive". It's comparable to Win7 and beats the pants off of XP, OSX or Unity.