Windows 7 fixes a number of vexing Vista problems, like User Access Control run amok and slow network copying. It has a crisp user interface. More options are hidden now, making most decision trees simpler -- unless you are wondering where the Performance power option disappeared to. The install was painless; Vista and all My Documents were even saved automatically into Windows.old.
But this is still a beta. Default screen resolutions use only a fraction of an LCD's pixels, a waste. None of my WMA music is playable because the online DRM gatekeeper is broken, so no sounds. And home networking is complicated by the concept of "workplace" that will have you walking (unhappily) around to the other machines in your house looking four levels down in a menu tree, only then to have to enter a 10-character alphanumeric, upper-lower case generated password. That's so you can see your other computers on a home LAN.
As expected, Windows 7 is a work in progress. On the whole, it's likely to turn out the way Microsoft (desperately) wants it to: successful. The beta is a lot more stable than even release candidates for Windows XP, so if you have a snowy day with nothing much to do, give the Windows 7 beta a whirl.
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