Well, I don’t think it is the ultimate tool since there are a lot of limitations of blogs:
Limited target group
It is only a small group of people that will read your group. To build a strong personal brand, you must reach a larger quantity of the people targeted.
Only a small group (of the small group that visit the blog), will interact with you online, which makes blogging mainly a one way communication.
Limitation of the written word
Branding is a lot about feelings, and while the written word gives the opportunity to think before you speak, you will miss out on the feelings communicated by body language, face expressions and tone variations of the voice.
With this said, I still think blogging is a good tool, but the brand needs to be govern in so many other aspects.
This post is orgiginally a replay by me in a discussion on XING.