Alexander was a great military genius and elements of this were his speed of movement, his military tactics and ability to adapt, and a charismatic and inspiring quality of leadership. Obviously, he was lucky to have the highly trained and experienced Macedonian army behind him. Alexander led from the front and, although this was undoubtedly an inspiration to his troops, he took foolhardy risks, displaying his irresponsibly at the same time. It is much harder to evaluate Alexander as a statesman. He had only just finished conquering his empire, and many of his administration could be seen as only temporary, however from Alexander's policies and actions, the evidence points to his lack of foresight and judgement in areas unrelated to warfare.
The view that Alexander was a brilliant military tactician is undoubted; Napoleon's verdict suffices. In the space of twelve years, Alexander's conquests stretched from Macedon to the Punjab region in India.
The few scholars who have doubted have either believed the fantastic legend that makes the Persian armies huge useless mobs, or have suggested that his success was due to Parmenion and his Companions. Alexander started, of course, with the advantages of Philip's army but Parmenion's death made no apparent difference as Diodorus tells of Alexander's consolidation of his father's gains: "Alexander brought everything into order impressively, and swiftly." This shows candidly that even early on, Alexander was a capable soldier in his own right.
Alexander met every opponent with different but appropriate tactics; "he handled the unknown foe--desert Turcomans, Indian hill-tribes, Porus' elephants--with the same certainty as Greek hoplites or Persian cavalry" (C.A.H. p 425). In logistical skills and planning, Alexander had a superb appreciation of the value of speed and mobility of the army. He taught the principle of "march divided, fight united". Arrian makes several mentions...