Don't forget that France surrendered.
This does not always mean surrender; think Napoleon's invasion of Russia. The difference for Russia in my opinion is that they had a large homogeneous land mass upon which to move and maintain their administration.
Similar reasons cost Napoleon dearly ~130 years before.
Also, Stalin's massive ego wouldn't allow a city named after himself to be taken by the Germans. That's the primary reason that particular city suffered the high casualties that it did. Stalin once told Churchill at the Tehran Conference that "when one man dies it is a tragedy, when thousands die it's statistics."[1]
[1] http://books.google.com/books?id=8fp1A2s6aQwC&pg=PA510&dq#v=...