I find that blogs have the tendency to be a bit more thought-out than social networking. Instead of tweeting or updating your Facebook status with whatever interesting thing comes to mind (whether it’s important or not), you have the chance to express your thoughts more fully.
However, blogs can be really obnoxious too, depending on the subject matter. Some blogs are really great, and these ones have a few similar traits:
-They have a clear direction and theme.
-The subject matter is interesting.
-They are well designed/organized.
-They are well written.
This is a generalization, of course. I’m sure there are some blogs that don’t meet all these qualities and are still popular. But I haven’t come across a really well-known blog that is just people talking about everyday trifles.
If you’re just going to make a random blog to talk about whatever you want in a stream-of-consciousness style, most likely people won’t want to read it. There’s nothing wrong with having an online journal for you and your close friends to see, of course; but you probably won’t become Internet-famous with it. It all depends, like @wundayatta said, on what your goal is with blogging.
I’ve also seen an episode of House where a patient was so engrossed in her blogging that she tried to base her decision of whether or not to get serious medical treatment with huge consequences on the opinion of her blog followers. And since obviously everything on TV is true, you know that this is something that could potentially happen to you.