I came across this article about END Footwear the other day. It has some legitimate points (for example, I'm not too keen on the fact that the "green" shoes are made in China, then shipped across the world for me to buy them), but I think it's a bit harsh and unfair towards a company that genuinely seems to be trying something new and beneficial for the environment.
What END is doing seems to be on the right track, and there aren't many other manufacturers actively trying to change the marketplace, so I give them credit.
The big question about shoes (or any product for that matter) and sustainability that I don't have an answer for is, "what's ideal for sustainability?" It's great that END uses a good chunk of recycled materials, but ultimately, these shoes are still going to end up in a landfill. But is the best thing using recycled materials or creating a product that is biodegradeable like Brook's is doing? The best thing would be a product that is both made from recycled materials and is biodegradeable, but that's probably a little ways out (actually, the real best thing would be a product made from completely organic and biodegradeable materials, but I don't want to run in hemp sneakers).