The problem, of course, with releases like Windows 7 is that the new operating system has already been torn apart and examined in great detail over the past 10-12 months, so there's little in there that will surprise anyone who has't been living under a digital rock the past year or so. I could list the new features and improvements, but you probably already know everything there is to know.
I'm sure the people who were really enthusiastic about Windows 7 pre-ordered it, and are currently tearing the box it comes in to shreds (or are still waiting for the mail man, as I'm anxiously waiting for my pre-order of "Borderlands"). For everybody else, you can of course buy a boxed copy from a retail store, but it's much wiser to simply wait until you need a new PC - retail copies of Windows are quite expensive, but OEMs get nice discounts.
If you do insist on buying a retail copy, you'll be in for a lot of work if you already have a functioning Windows install. Windows XP users will have to perform a clean install, which means backing up your data (you already have a backup, right...?), whereas Windows Vista users can perform an upgrade, but if it is wise to do so remains to be seen. Conventional wisdom tells us a clean install is better anyway.
Windows 7 carries with it a lot of expectations. The operating system has been very well received by the press, but the public will eventually always make up its own mind. Vista left a very bitter after-taste in people's mouths, and it's up to Windows 7 to wash that taste away. More problematic are probably the legions of Windows XP users, who swear by the ageing operating system. Getting them to switch to the new operating system could prove to be the biggest challenge for Redmond. And let's not even get started about companies and enterprises.
For what it's worth, I'm actually quite satisfied with Windows 7. I've been using it on all my machines (from an overpowered desktop to a small and tiny netbook) for about 10 months now, and I haven't really run into any problems with Redmond's new baby. I especially value the overall polish, something that was sorely missing from Windows Vista.
Have fun tearing Windows 7 apart today!