Wes Huntress has some. I agree with a lot of what he says, but not all:

The directive to land on the Moon by 2020 is not achievable given the agency’s current limited out-year budget, costs for Constellation development, and the looming requirement to support the International Space Station beyond 2015. The best approach to lower cost and sustained development is to leverage existing space transportation infrastructure to the maximum.

I absolutely agree with the second sentence, but not the first. It is possible to get to the moon by 2020, within the available funding. But in order to do so, NASA has to focus its resources on getting to the moon, in an affordable and sustainable manner, using that existing infrastructure. As long, though, as they focus on developing their own launch systems, it will never happen. And not just because they’re not very good at developing launch systems.

I wouldn’t emphasize the international part, either. I don’t mind doing partnerships, if they make sense, but we shouldn’t do things internationally for its own sake. I wouldn’t abandon the moon–I think that NASA should be developing a lander, but that’s really the only major hardware element (at least in terms of transportation) that’s lunar specific. We need to develop a general deep-space transportation infrastructure, and it NASA had focused on that instead of Ares/Orion, they’d be a good way down that road now.