Blogs are very versatile and can be used for almost anything, when it comes to writing or promoting products. Many folks enjoy the automation and easy-to-use publishing format. Posting on a blog can sure be done a lot quicker as opposed to building web pages on a site using old school site building tools and html code.
However, when it comes to search rank, I've always had better luck with the standard websites that are not automated - where you have to manually type in all of your meta tags and align your own images, text, and adverts via x & y coordinates, etc.
Personally, I like 'em both!