I agree fundamentally with a lean startup approach. I think the only thing to be careful of is shortchanging yourself. I think there has to be enough put out to test and get feedback on. It will be different for every project. Some can be built quicky, while others take more time. The trick is just to identify what are the core components that make the product. That's another advantage of a lean mentality, it forces you to focus on what's important and that can help the product evolve more potently I believe.
a question that is relevant but not touched upon by this article is how much to weigh feedback into the decisions you make about your startup.
while feedback is an absolutely necessary part of developing your idea, its also important that you have a clear vision of what you're trying to accomplish and not let feedback lead you astray from that vision.
disclaimer, i'm coming from an interactive design background, so may be a little more sensitive to crappy feedback that muddles my beautiful designs :)
