It's certainly more than just the button by the way, because the button is already in Win8 when you mouse over the very bottom-left corner of the screen.
We already knew the button was coming back. I can only imagine that some are struggling to work out what to do without a button, which I can well understand given some of the people I've worked with.
That said, if people are shown what to do, then they've been fine with it in my experience. I think where Microsoft have let themselves down with the new GUI* is with a complete lack of instruction. As far as I can tell there's only a short animation which shows while Windows is finishing installing (or on first boot up on an OOB system). Had they included a tile to guide users through doing this or that on demand, it would have been far better. I'm sure there's plenty of info buried away in a help file somewhere, but that's the issue - it's buried away.
I'd love for them to have given us the option of start screen or start button, but I can't see them doing it - they need to encourage developers to continue to add apps to aid their mobile platforms, and if everyone could switch off the start screen (and most would if it were an easy to see option), many developers simply wouldn't bother putting the effort and cost into programming apps and tiles.
Personally I couldn't care less. I'm not a fan of the start screen, but it doesn't slow me down in the slightest. I can still open programs in two clicks and indeed more of my programs are visible without having to go into All Programs. I can still open programs by simply hitting the windows key and typing a couple of letters. I still shutdown a PC by pressing the power button. The only negatives for me is having to dig into the charms bar to restart a PC, though that's still three clicks as it is with Windows 7 (unless I create a shortcut, though I restart so rarely its not worth it), and I'm missing the recent items for individual programs (obviously the Office suite have their own recent items and I can continue to pin my important items them in each Office program, but some programs don't have that recent list or the ability to pin items.
That said, I could happily continue working with Windows 7, though I'd miss a few features, GUI tweaks and the optimisation Windows 8 has had. As I said, couldn't really care less either way. I'm certainly not a fanboy and wouldn't encourage or discourage anyone against either, save for telling them that "this is the way it's going, so you might as well just do it now".
* and don't get me wrong, while I don't mind tiles instead of buttons, I'd have gone much further in changing the GUI and integrated Metro
into the desktop rather than having the current old flat, 2D and relatively useless desktop.