Well, I'd like to chime in here. I am one of those who really dislikes this auto-save feature. Acutally I downgraded from SL to Lion because I wanted this feature. Autosave and Versions. Finally getting rid of those Document piles v1, v2, v3, v3.2.4 etc.
But my disapointment was great and I honestly hate this implementation. I think most of us agree that saving our hard work in real time is basically a good thing. But, it is poorly implemented. This is why I think so:
Firstly, we all know that it isn't about the fact that the features are available but about how they are designed. It's about simplicity and usablility.
My example would be: One single keyboard shortcut is the quickest and easiest way to place a copy of your file somewhere and directly continue working while the old file is automatically closed, since you usually don't need it anymore.
Secondly, I haven't seen any case of "forgotten savings", the user is always asked whether to keep the changes or not. Clicking "Don't save" instead of "Save" would be a more than rare occurence.
Additionally I would say the counts for theneed of not-saving are much higher than the counts for the human error of mixing up "Don't save" and "Save".
Thirdly, try to find the right version of your text- or spreadsheet-document in that tiny starwars window if you have more than half a page filled. Hope your overtime will be paid.
What I would rather like to see is a less radical approach. Documents could be saved as versions in the background, so if you really faceplant dogsh't with "Don't Save" or you have a power loss on your 16GB MacMini, you could get the backuped status in a timeline.
Just imagine Autosave saves comments that are not intended for the customer/friend/professor/etc... urgh...
But, again...
This won't happen because there is no "Save" on the iPad. And that's the reason why they killed it on the mac. (In the first place I thought they were just smoking the wrong stuff, but since Phil said they will introduce the iPad saving style on the Mac... well...) Hope they'll come up with some fancy ideas like selling the good old folder as "Location" or whatever.
I work with complex documents in Numbers and I frequently have to try some "what if this or that" (similar to the creatives with image editing). Sure there are workarounds like clicking the top bar menu or duplicating the file in advance. But all of that isn't the way of simplifying or getting the computer out of the way. It's just the opposite. Too much sacrifice for a tiny bit of security.