I'm surprised by how many people will provide book reviews on Amazon, movie reviews on IMDB, restaurant reviews on Citysearch, etc. These people are using reviews as a way to both share with a larger community and to do some journaling for themselves. It's similar to traditional blogging.
A friend of mine and I started a website a couple months ago to allow people to describe places in San Francisco using blog-like entries, maps, tags, and photos. Initially, we thought that people would use the site primarily to criticize or review places but instead the posts have largely migrated towards journaling, as you suggest here.