My class on The Great Transformation has been going through The Protestant Ethic and the Spirit of Capitalism the last two weeks, which has led me to think about the work in some depth. One thing that has struck me is that most of the criticisms of the work that I have run across are fairly shallow (I'm not saying deeper ones don't exist, only that there are plenty of shallow ones out there), in that, often, their critiques are things that Weber already addressed in the original book!
There is a good history of thought paper to be written here, with a target journal like the AJES. I'd like to find a co-author who would want to help with the research into popular critiques of Weber's thesis. Get in touch with me in the comments section at my blog, on Facebook, or via e-mail if you are interested.