Young's experiment or why the light can't be described as a particle

I point out that Feynman, in his 1979 Douglass Robb Memorial Lecture, part I (actually entitled "Photons - Corpuscles of Light") on QED, video freely available at http://vega.org.uk/video/programme/45, asked this very question. He answered definitively that Newton was correct and that light was indeed a particle which, however, propagates according to the usual q.m. laws of adding complex amplitudes, thus reconciling its particle nature with observed interference phenomena. Furthermore see his closely related answers on this question at http://www.youtube.com/watch?v=_7OEzyEfzgg&feature=related.

The determining evidence ruling out waves includes 1. the photoelectric effect since waves can not cause ejection of electrons with the same frequency energy relationship, and the non relationship between the E field amplitude and energy 2. Compton scattering (not mentioned in his lecture) not explainable under a wave theory 3. An argument he alluded to relating to the equation for scattering multiple particles not corresponding any more to Maxwell's equations (which I don't quite follow). With the adoption of the probability amplitude propagation theory of QED, apparently no evidence is against the particle hypothesis. (I myself would also like to see a QED derivation of the old Einstein entropy density of black body radiation in a closed cavity, however, i.e. the one that looks like 1/2 particle and 1/2 wave)

Note related to a comment below:I previously (mis)attributed these arguments to his 1964 Messenger Lectures at Cornell, available online (only for PC's?) here and later published as "The Character of Physical Law", but the correct ref. is as above.

PS. I myself do not feel that the question is confused at all, and actually voted it up, but it is the sort of question that often gets many confused answers. I'm not too sure how we should handle this)

When we say it doesn't behave as a particle, we mean it doesn't behave as a classical particle. But it does behave as a particle, in the sense of an elementary particle, which shares some characteristics with classical particles, and some with classical waves.