enter to rename is just a lot faster for me than f2, bigger clearer button makes it much faster. from a usability standpoint, i'd rather rename easily than open easily.

I agree that f2, as an interface key, is less convenient that enter. However, there's a principle that more common interface operations should have shorter paths to activation and less common ones can become more and more inconvenient by being buried in menus or hidden behind some non-discoverable 3 or 4 key combination. The key side benefit is discover-ability. Renaming is just simply not as common an operation as opening/running. Unless you spend your days renaming lots of things and only open on occasion I guess.

But this principle, shorter path to common operations, is violated all over the place in OSX keyboard land, but rigidly followed in OSX mouse land and iOS touch land. Whereas the inverse is probably true for Windows.

also maybe it's because I've gotten used to the cmd+up and cmd+dn to go up and down directories (and also open files). in the end, we're all arguing a matter of preference.

I agree in many cases. cmd+up/dn is just as good as the windows equivalent. Being different isn't being worse, being worse is being worse.

it's equivalent to minimizing for windows. I want my mail app and calendar apps to be running and able to give notifications, but the window itself doesn't need to be rendered. Also, stuff like my browser that i open and close constantly doesn't need to be reloaded from the HD every time I open it, I don't want to see photoshop and office splash screens and wait the extra seconds to load an app every time i open a file simply because i closed the last window last time.

There are three things you should be aware of. In windows land, you can have background services running that handle notifications. You don't need the app open if they've designed it that way. Often they'll even stick a little icon in the taskbar you can click to open the app. Second, often pieces of windows software will stay resident in some part so that opening them a second time is much faster than the first time. Firefox for example takes a good 20 seconds to open on my system (what with all the extensions and junk I have in it). But only 2 or 3 seconds after that. Chrome opens so fast the first time I may as well have it minimized. Office apps in particular do a good job of this. Third, because of the MDI style in Windows, closing a document in an MDI style program is clearly not the same as closing the application. Many applications will stay up after closing the last document, like Photoshop, but it's clear that it's open and not just indicated by a generic toolbar at the top of the screen that could pretty much be from any old open app -- which is a consistent problem in OSX, "I've closed all my documents, now is the software closed or not, dunno, there's a toolbar that looks like every other tool bar for every other app, perhaps it is closed and I've just switched to another application, nope! It's still open". Not saying this is better, it just falls into the "different" category. Once you get used to it you go to close the app by command-Qing everything. But it's hugely annoying going from Windows->OSX and never ever ends up "feeling" right.