I don't know much about philosophy, but I know that Less Wrong's opinion of it is pretty low [3].
Eliezer probably talks about quantum mechanics more than most philosophers, so his recent explanation [4] of how statements about day-to-day objects can be true despite the fact that only fundamental particles really exist is probably original.
As far as I can tell, the introduction of a lot of terms from physics doesn't fundamentally change what he's doing philosophically, which is largely a rehash of logical positivism. I could be wrong, but he's setting off all sorts of "don't waste your time here" bells in my head, so I'm not going to really dig into him and see whether it's a waste of time to do so.
As someone in the comments notes, he incorrectly dismisses his own example that illustrates why he's not a logical positivist. A momentary cake in the heart of the sun would have physical consequences in the universe that a (sufficiently advanced) being could detect (or not detect), so a logical positivist would agree with him that the statement is meaningful.
I don't know that it's fair to say he's just a logical positivist. But he seems intent on layering LP with a lot of jargon from physics and information theory to create distinctions without difference.
Eliezer probably talks about quantum mechanics more than most philosophers, so his recent explanation [4] of how statements about day-to-day objects can be true despite the fact that only fundamental particles really exist is probably original.
[3] http://lesswrong.com/lw/frp/train_philosophers_with_pearl_an...
[4] http://lesswrong.com/lw/frz/mixed_reference_the_great_reduct...