Microsoft makes some valid points, bringing up the fact that you can't get a Mac with a Blu-ray player, TV tuner, Memory Stick reader, or built-in 3G wireless. They also mention the world's most popular computer games aren't available for Macs and that PCs give you a lot more choice and capabilities for your money. As it is to be expected from a marketing campaign, Microsoft overlooks any positive aspects its competitor may have, but it's rather comical that they claim productivity documents on a Mac "might not look right and your spreadsheets might not calculate correctly," despite the fact that they make a Mac version of Office and it's not like the suite comes free with Windows.
The site also displays a feed of tweets mentioning Windows 7 in a bid to show users' opinion about the OS. You can read some of the other assertions made by Microsoft on their site, and most importantly, do you agree with them?