As I tossed back at my advisor in my thesis defense, this question in short comes down to the eye of the beholder. To Greeks, the Argead king may have been Greek, but usually just when he insisted upon this right. To Macedonian kings they sure were Greeks, to the Macedonians themselves they were not. Yet they are notably included in the Iliadic tradition of Greeks. Philip married women who clearly were barbarians, yet also a woman who traced her lineage to that great Greek hero Achilles and lived in the same mixed state as he, all the while holding a majority vote on the Amphyctonic council through his position as tagus of the Thessalian League. Although this quagmire of evidence leads nowhere or in circles quite quickly, there is much that suggests that Macedonia was in fact Greek-esque, but resembled the less civilized, Homeric kingdoms of Greece, rather than truly civilized peoples.
One of the leads I would like to know more about is marriage practice in Macedonia. By all accounts men were permitted to have multiple wives if they could take care of them and Philip went so far as to marry in order to solidify his conquests and allies. There was differentiation between prostitutes and wives, but other than that I have been unable to make out much. In contrast, each Greek group had their own practices, and while some were eccentric, they were also largely monogamous. From this angle, Macedonians were not Greek.
A second, non-Greek, aspect to the Macedonian identity was the distinct lack of poleis. There were some of these city-state units, but they were usually reduced solely to the city limits, while the surrounding farmland, which was always the second constituent piece of a polis, became property of the king who then distributed that land amongst his supporters. Such was the case with Amphipolis and the Olynthian League on the Chalcidice. Macedonia did have limited representation in the form of the Army Assembly and the King often yielded to the political wisdom that consulting and heeding advisors often resulted in smoother function of the kingdom, but he didn’t have to.
In short Macedonians were not Greek, but they were Greek enough to push that identity when it suited their needs. All of this took place while keeping a distinct ethnic identity.