Awesome to see something like this open sourced. Definitely going to check this out. For those who don't have the resources available to manage this kind of infrastructure however, you may wish to look at Cloudinary (http://cloudinary.com/).
For low volume sites, photon works well enough on a single Heroku dyno (especially if you put a cache in front of it).
I'm sure it works great. But it's one other piece of infrastructure to deploy, monitor, and maintain. Depending on what stage your at and whether or not photos are core to your business, I think (at least temporarily) a hosted solution is better for some.