I agree with a lot that Steven_D says, blog are good, they are a good communication tool, they are easy to setup, they are easy to get into Google's index (I recently started a blog on blogspot [link removed] and it got included in Google index the SAME DAY) and they are very popular.
BUT, the biggest problem with blogs are that they are easy to setup, they are easy to get into Google's index and they are very popular.
The real question is how do you make your blog stand out from the rest.
Gary