Just reading his frequently asked questions was probably enough for me to say I agree with him. His proposal is idealistic, though. Bioethics is an area where we know exactly what would increase humanity's well-being, but Sam Harris's modest proposal isn't going to sway anyone.

Basically, it's cool that someone's being sane about morality. For anyone who disagreed with or didn't understand Eliezer's sequence on the subject, this seems like the next best thing, if you supplement it with knowledge of evolutionary/cognitive psychology, rationality, signaling theory, et cetera.