Depends on what you want. If you want a personal blog, those are pretty easy. (all blogs are time consuming, which is why I don't have one). If you want a professional blog to help you get a leg up in whatever industry you're looking at then those can be pretty difficult. You have to know what you're talking about, be able to write in a way that your peers understand as well as people who might be interested in your services, while keeping up to date with all industry content, as well as providing content to regular readers on a consistent and timely basis.
It's not for everyone but if you've got the time, go for it. Greg as a pretty good blog that I enjoy reading, ask him for some pointers.