From what I can tell The Empire Strikes Back and Star Wars are neck and neck in the race to claim the "Greatest Star Wars Film" title (and perhaps greatest film period).
I never understood why. To me Star Wars is vastly superior. The action is better, the ending is more satisfying, the soundtrack is better and acting is fresher. But the biggest problem is that: "[Empire] suffered from . . . the classic problems of being the second act in a three-act play."
Then I watched the original unaltered editions last week and I gained something of a newfound respect for the ending. The middle is still muddled, but the direction and pacing of the last 20 minutes or so deserve more credit. Kershner does a great job of easing up on the throttle in the falling action, giving a few jolts of excitment to keep the movie from going into free fall (as in Return of the Jedi). The scoring is also at its best in the series aside from during the trench run.