I think it's great if you have a project that is ongoing. It's a wonderful way for your fans to show support while you create it. A great reward is exclusive art or progress shots from such a project. Something that let's supporters be involved in some way.
There are a lot of people jumping on the Patreon wagon, but I think that some care should be used when coming up with what you want to use it for. I think it's perfect for Web comics or youtubers, or anyone who constantly creates and shares content for free. It wouldn't really be good for, say, sharing commissions that you were already paid for. Or at least, I have yet to see that be a successful method.