The first thing most people think when they turn a Mac on for the first time is something along the lines of “Wow. This looks cool.” Then the next thing you notice, or more accurately, don’t notice, is the act of using the OS. Once you get used to how everything works, which doesn’t take long if you’ve used another OS (read: Windows) before, you don’t have to think about it. It’s intuitive enough that you just do what you need to do without having to think about it much. You don’t have to worry about the OS itself much either, except when you need to do some occasional maintenance.
The Mac OS is
Those three bullet points are some of the most important things to think about when it comes to web design. Obviously you want to have a good-looking design (don’t tell me you like GeoCities-style pages…). The other two points are very important. If you must have a horrible-looking design, the second two points are worth putting some thought into.
Simplicity doesn’t necessarily mean having a Google-esque design. You could classify Digg as a fairly simple design, though not to the point of Google. Ideally you want to simplify elements of your design, to make it more usable, but that doesn’t mean you have to not have any images or color.
Ideally, you want to have a design that’s intuitive and easy to use. That means simplifying your navigation, so there are as few choices as possible, yet enough to easily find certain information. You want it to be noticeable too.
The Mac OS has many of the elements of a “perfect” design, and I’ve only touched upon them lightly here.