I also found it to be an excellent blog. I have been reading for quite some time now. As far as I know Michael is out of Iraq for now, but reading from the beginning and getting a sense of how things have changed and how events are being shaped gives one real sense of how we are doing there. You can sign up for his mailinglsit so that you get an email reminder whenever he puts in a new entry, which is about once every week.
My opinion is that 20 years from now when historians are looking back at this time and are gathering primary documents for books and textbooks, Michael Yon's blog will be one of those controversial, but hugely important sources.
Drew
Edit: PS "Gates of Fire" is some of the best reading. But like Band of Brothers, has a lot more meaning if you read/watch from the beginning.