It's interesting how different people react differently to this work (as different people react differently to modern teachers and scholars I guess...). I suspect it depends a lot on how one first encounters the Dhamma. For me I could see the advice of my teachers in various aspects of the meditation instruction, so, like ihrjordan, I have found parts of it extremely useful. There is a lot of very helpful practical advice on meditation that appears to me summarise the experience of a wide variety of practitioners. So, in that sense, I tend to regard much of it as if it is a collection of dhamma talks by various ancient teachers.
Most criticism of the Visudhimagga that I've seen tends to revolve around subtle doctrinal points (though the article in this thread is an interesting exception: ). The middle section that summarises the Theravada doctrine is rather heavy going and, of course, a number of modern interpreters of the suttas have doctrinal differences with the Abhidhamma and ancient commentaries. However, I've never found such intricate differences in doctrine to be particularly important in actual practice. To me it's just a framework, not an end in itself.