The supply issues in the basic game (up to the 1.4 patch, which only half-fixed them) were VERY real, despite the condescending remarks about "use arcade mode" offered by a few tactless individuals. I've had divisions go out of supply, and stay that way for weeks until I moved them, a mere 3-4 provinces from the capital over good (6-10) infrastructure (this occurred in games playing GER, Nat.Chi., and HU). Meanwhile, other units 60+ provinces away were getting adequate supplies over some absolutely miserable infrastructure (GER's troops deep in SU; Chinese troops fighting in upper Manchuria and the Korean peninsula; HU's troops through Turkey, around eastern end of Med, and fighting to take Suez), but that unit sitting RIGHT NEXT TO THE CAPITAL was starving. Moving it one province solved the problem; don't tell me that's "poor logistical planning" on my part. With the 1.4 patch, it rarely occurs, and sometimes fixes itself after a few days, or else you have to move the unit into any adjacent province, but it's still kind of frustrating to have it happen for no discernable reason.
Anyway, as stated, the game straight out of the box bordered on unplayable, with massive fundamental game flaws: WWII usually didn't even occur unless you deliberatedly started it, and even then only massive abuse of spies and influence could make the game so much as vaguely resemble the historical war (AI Poland allying with Italy or Hungary who were already in the Axis and causing the various Axis countries to declare war on each other when Germany invaded Poland; Australia rushing to join the Axis by 1938; Japan invading Finland; US entering the Allies in early '37, etc.). The patches up to 1.4 fixed just about all of the consistent total game-breakers, but there were still occasional hiccups where the major powers self-destructed (GER invading India, then repeatedly sending reinforcements when supplies ran out and "fighting strength" fell, until there was 1 divison left on the entire Russian Front) or failed to take the most basic defensive steps (France abandoning the border fortifications next to Italy; Germany pulling all of its troops off both fronts to sit as "superstacks" in Danzig and Amsterdam), leading to an absurd turn of events, or a restart in hopes that the problem wouldn't recur.
I don't have the expansions, but understand that most of the remaining issues have been addressed, although some not entirely solved.