When I started my blog I was the same way, half-hearted. I made one because it was "another way to promote my shop." My heart wasn't in it. Last March, I started my blog up again, redesigned it, and really put effort into making it a site that I would enjoy reading.
I really can't explain how beneficial it has been not just for my business, but myself. Yes it is a lot of work keeping up with my shop, twitter, facebook and blog. But it's been so so worth it. My shop is doing better than ever and I know part of that is because of the support and friendships I have made through blogging. You will be amazed at what a networking world there is out there with blogs.