It's a common trope that Hitler screwed up the Axis plan at every twist and turn. However, I've been doing a course on WW2 for a while at school, and as far I can see, he only started losing it at Stalingrad and afterwords, and before that he was quite sane and did things kind of sensibly.
For example, during the opening weeks and months of Barbarossa, instead of simply rushing for cities, he deliberately ordered tanks to outmanoeuvre and encircle large Soviet armies. This seemed like a brilliant plan, and although the Germans still lost, massive armies of several hundred thousand Soviet troops were captured almost immediately following the attack.
So, is the "Lol, Hitler so dumb" argument justified, or is it just the benefit of foresight and our misconceptions?
What you're referring to are operational decisions, not strategic ones. Operationally, Hitler has been described as a "gifted amateur": he had some good ideas, but the nature of the amatuer is that a professional usually thinks of it first. For example, he enthusiastically supported the move through the Ardennes to outflank the Franco-British armies in Belgium in summer 1940, but the flanking movement had already been suggested by Erich von Manstein, who took it to Hitler to get round the Chief of the General Staff, Franz Halder. Halder was desperately unenthusiastic about fighting another war with France and Britain and had been doing everything he could to make an offensive look unacceptably costly. Furthermore, the decision to aim south for an encirclement near Kiev had been made in the Lossberg Plan for Operation Barbarossa as early as September 1940, so moving the schwerpunkt south was hardly something Hitler came up with on his own. The German General Staff was in fact fairly evenly split over whether to continue to Moscow or go for Kiev - despite the intrigues of Halder, it was recognised that Army Group Centre needed time to take stock, reduce the massive kessel behind it that it had created at Smolensk, and let its supply lines catch up.
Moving on to strategy, the decision to invade the Soviet Union was a strategically inept one in itself, and in particular, the decision to invade while Britain remained in the fight on Germany's western flank. While Britain remained unconquered, it could continue to blockade Germany, continue to bomb German cities by night (thus incidentally draw a great number of Flak 88s, one of the only guns the Germans had that could penetrate the T-34 at range, away from the front and back to city defence duties), and serve as the forming-up point for the Arctic Convoys to the USSR and for the planned invasion of Europe once the Americans entered the war. Every other mistake - from the Wehrmacht's grotesquely inaccurate assessment of the Red Army's strength, to its racially-driven mistreatment of civilians, to its brazenly cavalier logistics planning - only served to intensify the impact of this single utterly incompetent decision. The only possible way Nazi Germany could have won in the Second World War was to not be Nazi Germany.
Sources:
Robert Kirchubel, The Atlas of the Eastern Front, 1941-45
Robert Kirchubel, Operation Barbarossa: The German Invasion of Soviet Russia