There are a few things I like about Web 2.0, like the AJAX programming technique, but its a very exclusive list.
Tags and blogs I think are completely useless. I have yet to actually click on a tag, let alone tag something myself. User generated content is usually crap. Blogs...I don't read them unless its a friend personal type log of their life. I really don't care what some no name has to say about global politics.
Yes, he makes the point but not firmly enough. Web 2.0 has nothing to do with tags, blogs, styling or AJAX. It's a definition for structure of a web application or interaction. You need to visit the O'Reilly site to get the actual description.