The most negative part of Windows XP seems to be the activation of the system, which can only be done on one computer per license. The corporate will probably not have a problem with this; he is buying it for or together with a complete system that probably never will need a reinstallation. The biggest problem is going to be for the enthusiast who might change his system such that a reinstallation will be necessary quite often. It might for him become a hassle to reactivate the license via Microsoft's support all the time.
XP has a lot going for it. It's a little pointless to compare the performance of XP to previous versions of Windows. The reality is that every operating system from Microsoft uses more resources and takes up more of your hardware than the one preceding it. We wanted to look at it from the point of view of guys who have to sit in front of the screen 10, 12, sometimes 16 hours a day. So, a new interface is welcomed, if it is good. XP's new look and feel seems to be an improvement.
The other really noticeable feature is that XP's remote assistance and access tools are going to directly target freebie applications like VNC, and things like pcAnywhere, or GoToMyPC. Microsoft is integrating features into the XP OS that will, in effect, deliver remote support and access technologies to anyone implementing an XP server. The remote assistance and access tools in XP worked very nicely, and are integrated with Microsoft's Instant Messaging so, they're pretty user friendly. A boon for help desk staff, and maybe a nice way for the average home user to lend a hand to grandma, or that sibling who never seems to be able to configure his PC.
Maybe one strong argument for XP is that the sum of the parts is greater than the whole so, it's worth that upgrade price. On the other hand, we're using XP here in the office on a couple of computers, and heck, it's not bad. We'd buy into it. Barring the "anything-but-Microsoft" argument, there isn't a good reason not to take the plunge with XP. Once the full version is out, it'll be time to test out its gaming performance, and also, to look out how the more popular applications will take advantage of XP's features.
So, it might be nice to be down on Microsoft because, they are evil capitalists with no soul (or, at least some people say), but that's not a good enough reason to shun XP. It might also be true that the Justice Department didn't do much of anything to thwart the barriers that Microsoft's monopoly puts in front of other PC software developers, but that doesn't really impact the fact that XP does a good job.