I have read and listended to a lot of what Bill Hill has discused and I respect his opinion a lot.
He has made a post about the decision to turn on Cleartype in IE7 Beta 2. I recommend that if you read the post if you want to learn more, but to soundbite [or rather "lift"] from the blog entry.The decision to turn ClearType on by default in IE is unusual, but was made because solid research over the past few years has shown conclusively that it improves reading - the task at which IE users spend most of their time.I have not noticed any problems with cleartype, I find it easier to read text that is cleartyped, for some reason I concerntrate more. I have however, noticed problems with Blogger [and other sites] with IE 7 Beta 2 rendering the pages correctly.