I've been satisfied with every version of Windows. That's my point - from my perspective it's just an OS. As long as it does what it's supposed to do I'm happy.
Originally, an Operating System was the base level system on which everything else would be built. IBM ROM BASIC is a good example of this; generally, you can't really do anything particularly useful with the interpreter on it's own, but if you write BASIC programs you can create file managers and small phone number database programs. File management via the BASIC functions would be time consuming and prone to errors, as well.
Then you have DOS, which, as the name implies, is not just an Operating System, but a Disk Operating System. This brings along with it several implied features, such as the ability to move, copy, rename, and generally manipulate files directly from the OS, whereas many previous operating systems for the PC would require separate programs to perform those features. This "base functionality" was of course also present in UNIX, with the various file manipulation commands.
As MS-DOS grew, so too did it's scope. Originally only a command shell for executing other programs with some basic file management capabilities, it expanded to include a vast array of different built-in programs, to do such varied tasks as edit text documents (using edit) to performing memory user analysis (MemMaker). In this time there also sprouted the Windows Shell, which at the time was nothing more then a desktop environment that ran atop DOS itself, and graphically represented many of the functions that could also be done in DOS; it also made writing programs easier, somewhat; the API is and was huge, but at the same time, learning it meant you didn't have to write all sorts of drivers for all the different printers, display devices, and other stuff your program would use; Windows would handle the "translation".
As Windows matured, so too did the toolset. With the consumer switch to the Windows NT codebase starting with Windows XP, many people found they could no longer apply the various "tricks" they learned with 9x and earlier with it, since it was no longer merely a shell running atop DOS. Things like fdisk were replaced by equivalents that ran within windows; Nobody can possibly claim that Disk Management is a step backwards from fdisk, for example; the former required you to reboot your machine into what for all intents and purposes was a totally different OS (MS-DOS) run fdisk, and perform any number of actions using text-based prompts, then reboot again. Now, partitioning drives other then the system partition no longer requires a reboot at all. Improvements all across the board have incrementally added themselves to the Windows Operating System; saying "my favourite feature is that it works" is pretty ridiculous, since that's sort of an implied trait. This thread clearly was started in the interest of garnering discussion on the various new features that windows 7 has added to the OS; Windows 7 has added more visible features then almost any other incarnation of Windows for quite some time; a lot of these revolve around Aero and window management, which has been a sore point among a lot of windows users.
Basically, assuming that an Operating System has to only "work" to do it's job is rather minimalistic; Take a standard DOS 3.1 installation. You can copy files, you can move files, you can rename files, you can create folders, you can delete folders, you can edit files using a line editor.
However, if you want to edit a text file using a standard Word processor type display (whereby you can see and navigate through larger chunks of text) you would need to buy a third party program or find a free alternative, the latter of which was not as easy as it is today.
This highlights something, though. What we have had since windows 3.1; The standard Windows Editbox.
The otherwise simple EditBox I am typing in, for example, comes free with Windows. All Programs can use and reuse this component; the thing is, what this component does- edit text - is something that you could expect to shell out a good deal of money to do with your old DOS PC (DOS 6 and later are exempt, since they come with EDIT, of course). What this also meant was that any program that needed the user to input text would often do so in the form of a standard prompt, whereby the user could only edit a line of input until they press enter, and after that it is essentially "locked in". Go ahead and do a copy con filename.txt and see how powerful that editing ability is.
More full-featured programs would implement Editboxes on their own; Microsoft Works, WordPerfect, Word for DOS, etc all present Editboxes in dialogs and so forth. However, there is something important of note here; the editbox as implemented by one application was unlikely to act and behave like one in another; Cut could be Shift-Delete in one, and Control-X in another; there was really no way to tell. Additionally, the editbox was essentially "sealed" in that nobody else could leverage the abilities of the editor for their own purposes.
In this sense, Windows is more then an Operating System, It's a Rich Desktop Environment; this is truly demonstrated since it has a Software Development Kit, it's own set of Rich APIs, and innumerable reusable components that behave the same regardless of what program is using them. This is something we have all come to take for granted; the fact that an EditBox in one program will almost always act the same as editboxes elsewhere. a Command Button in one program will behave similarly to a command button in another program, because they are, by definition, the same button. Just by typing into this textbox, I am leveraging any number of otherwise invisible Operating System features; to discard these features as merely extraneous fluff on the basis that all you need is the "Operating System" is to express ones ignorance on exactly how much of this fluff we all depend on every single time we use the computer. When was the last time, for example, we needed to edit our config.sys and autoexec.bat file in order to install drivers? Not for quite some time, since windows now essentially does it automatically for us; and in those cases it doesn't, you run an installer and your done. You don't need to worry about IRQ's or DMAs, we no longer need to flip jumpers and DIP switches around to manually configure our add on hardware; this is because the Operating System does it. However, one could easily presuppose that such functionality is quite outside the scope of an Operating System (DOS doesn't use it, and it's an Operating System) and therefore it's useless fluff. We should discard this fluff, since it's not truly part of the operating System. This is the sort of implication one makes by making blanket statements about how we shouldn't really even be worrying about new features in Windows since it's "just an OS". The Operating System is still the single most important piece of software on a PC; it dictates what you can and cannot run, and it essentially determines how you interact with those programs you do (with the aforementioned predefined classes). The fact that almost all Windows' Windows have the same management functions (close, minimize, maximize, restore, etc) is a testament to the fact that the Operating System and the programs you run are not separate entities, they work together. If your Operating System is slow or badly written, so to will the programs you run on it.
Poll