Many "professional philosophers" seem to be completely certain that "The Moral Landscape" is based on some egregious and rather embarrassing, fundamental oversight. Actually, these philosophers have no right to condescend, because their arguments are almost infallibly pre-empted and brilliantly eviscerated in Harris' gem of a book.
Amusingly, some philosophers try to justify their condescension by delving into nuances which could not possibly be generally agreed upon. That's not how condescension works. If you're going to accuse somebody of committing a foolish schoolboy error, then you actually have to provide evidence of ignorance of at least one point of consensus. It's obviously circular to accuse Harris of being ignorant about a point of consensus given that the ENTIRE PURPOSE OF HIS BOOK is to deconstruct this very consensus.
Harris' analysis, whether you have reservations or not, is undoubtedly more interesting than the endless reiterating of the misleading bromide, "You can't get an ought from an is".