I don't think anyone would buy a Mac just to run Windows on it. You don't buy a Mac for that, it just makes it less "scary" for Windows people, knowing that they can use Windows just the way they did before.
I think the stupidest thing in Windows 7 is that it can run Windows XP, which means that it's the only way you can get some programs to run on Windows 7.
I also think (but this is just my personal opinion), that Windows XP looked quite all right, I mean the interface, especially if you installed a theme called Royal Noir, which I really liked. Then Windows Vista started looking really bad, I really think it has too many different textures, colours, transparencies and stuff that don't contribute to making the system more understandable, they're just a show-off of wasted CPU power. Like Flip 3D, it's not useful like Exposé is, you can't use your mouse to choose the window you want, you just have to keep pressing WinKey + Tab to cycle through. I've seen some screenshots of Windows 7 betas and I think that it's even uglier than Vista, which means that Microsoft is going in the wrong direction (in my taste) of design.
And as everyone says, "it's still Windows", it's still going to bomb you with warning dialogs, it's still going to make you run wizards, it still will require lots of 3rd party software, for example, for your WiFi card in your laptop, you'll still have 4 icons in the task bar blinking and warning you about stuff you don't care about, one telling you that "the network has limited connectivity" when you're perfectly well connected, one saying that your virus database is out of date, etc... And then those drivers eventually run into some problem, you install another one, but the old one is somehow still there, causing conflicts, etc...
That's just my experience, and Windows 7 won't change all that. It might make better use of the CPU, it might have cool functions, but overall, I don't feel like "oh that feature would be useful to me". Windows is going along with what's inevitable: new features, slightly faster, etc. It will still be really darn slow if you don't format and reinstall it at least once a year! And then you start tweaking the registry, and everything goes fine, until one day an installer won't install an important program for some reason, you don't even know that you did something wrong in the registry 6 months ago to stop an annoying notification or a useless program from starting at login.