h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Blitzkrieg ground to halt in the winter of 1941 when the German forces reached a distance of 30km from Moscow.
Overextended supply lines robbed the advancing panzers of oil and ammunition, and the temperatures of -40 critically affected the german troops as 'General Winter' once again came to the aid of the Russian people.
Blitzkrieg was hugely effective over the relatively short distances of the French and Polish campaigns (though Hitler's ineptitude at Arras hamstrung the plan and led to the evacuation at Dunkirk). Over extended distances it proved far less effective, particularly as german Armour proved to be over-complex and unreliable.

If I remember my history a problem in russia was that panzers used deisel fuel which turned to jelly in extreem cold and the "take no prisoners" order made the Russians fight harder.

When was that order issued, exactly? I know for a fact that there were at least hundreds, if not thousands, of Russian prisoners taken in Stalingrad.

~*~Over extended distances it proved far less effective, particularly as german Armour proved to be over-complex and unreliable.~*~

That's not really a fault of the tactic though. More the technology.

http://en.wikipedia.org/wiki/Battle_of_Arras_%281940%29
First of all, Hitler wasn't directly in charge at Arras, so don't blame him personally for that. Second of all, I would say that it wasn't any fault of the German commanders, but rather more the fault of British tanks having superior armor at the time.

And it's possible that Hitler believed he could convince Britain to form an alliance with Germany; wiping out 300,000 soldiers certainly wouldn't have helped that, and so he may have allowed them to escape. Still a mistake though.