But, what do you do when you have multiple windows of different apps on the same screen? The Windows 7 Superbar can't do anything about this when you want to view all open windows at the same time so you can choose the one you want to get at.
SL's new Expose feature allows you to see all available windows from all open apps rather they are on the same screen or in different Spaces. You can also drag and drop files from one window to the next using Dock-Expose. All minimized windows and Expose windows can be easily viewed in full size by pressing the space bar and highlighting each window.
There's so much more that SL's Dock-Expose can do over Windows 7's Superbar.
I agree that if you want to see all windows, Win7's way isn't particularly efficient. However, most of the time you do know what app you want so it isn't that tricky. But if you want you can install Switcher, which replicates much of Expose's functionality and works very nicely and certainly far better than that crummy Win+Tab view.
I never use Dock Expose in OSX though because access to it is just plain slow. I hate anything that requires me to hold a button over something, I prefer click-and-it's-there behavior. Maybe there's a Dock Expose shortcut key I don't know about?
As far as closing apps vs. quitting in OS X, I understand your concern since it's not as cut and dry as how Windows does it but Macs are document based and Windows is application based. Opening apps in OS X presents the document while the application runs in the background. When you close a window only the document quits, not the application. The only reason an app will quit when the window closes is when it serves no purpose without the document window, then it will quit such as System Preferences, iPhoto and iMovie.
In Windows the application is built into the document so when you close the last window the whole thing quits. Honestly I hate it this way.
I on the other hand find OSX's way confusing at times and useful at others. When it doesn't work is with apps that do nothing if no windows are open and you click the icon. For example I've set Textmate so that it doesn't open a new file when it runs so if nothing is open, clicking the icon does nothing but activate the app, which is not at all clearly indicated in OSX. You can only spot it from the top bar changing. Apple should really add some kind of indicator over the currently selected app icon to note that it is activated.
But since computers nowadays are powerful enough to have many programs open without turning into a slow sputtering mess, not reloading them all the time has its uses. Windows Vista and 7 work around this by caching the programs but it's still slower than having them open all the time. I assume that when SSDs become the norm having the program open or not will be irrelevant and in that case Windows' way may prove to be better.
I would really like to see Windows 7's window movement options in OSX though. SizeUp replicates them to a degree but they don't work as nicely. Another thing I'd like to see is OSX being able to remember window sizes for different displays. I use a 24" external display with my Macbook at work and a 30" display at home and the windows always shrink when going to a smaller display. This is all fine but they should also resize back up when moving back to the higher resolution display. It's also laughable that OSX still has these 640x480 or 800x600 windows in stuff like Open dialogs etc. Win7 knows the display resolution and sets the default size accordingly.