The Battle of Yavin has been won. The Rebels have been celebrating, but it's short lived. The Empire has driven the Rebels from their base, and have begun an exhaustive search across the galaxy. Darth Vader has also begun an extensive search for the young Jedi Luke Skywalker, in an attempt to turn him to the dark side of the Force. Settling on the remote ice planet Hoth, the rebels have stayed hidden, until the Empire dispatches probe droids to search for the new rebel base. Upon finding a power generator, a legion of AT-AT walkers and AT-ST walkers are sent to the planet for a final annihilation of the rebel alliance, and the capture of Luke Skywalker.
Directed by George Lucas' old mentor, Irvin Kershner, ESB marked the first time the director had directed special effects. It certainly doesn't show, as they are even more awesome than in the original Star Wars from 3 years previous. Featuring more ships, bigger battles (Battle of Hoth, anyone?), and the first appearance of the old Jedi Master Yoda (back then anyway), ESB took what was great about ANH, and ramped it up tenfold. Yes, it was about 10 minutes longer, but it packed in much, much more. A chase in an Asteroid field, a bounty hunter named Boba Fett, a lightsaber duel between Skywalker and Vader and THAT plot twist, it's easy to see why many people prefer it to RotJ.
Another thing that's better is the music. Introducing the Imperial March for the first time, it gives the film a more darker tone which, in my own honest opinion, works a treat and helps to drive the film along. The script is also a lot stronger as well, which does go to show that back then Lucas knew what he was doing, and that Attack of the Clones was just wrong on so many levels (don't forget the lines in RotS as well: "I saw a holofilm of him.......killing younglings!" although that could just be Ewan MacGregor's poor delivery or bad directing).
If you were brought up on the original versions of the original trilogy (like I was), then you'll probably say that ESB is the best out of the whole lot too (although there are others who say that Jedi was better). It is the better of the original Trilogy (with ANH just a whisker behind), and the better of the whole saga overall.
You don't know the power of the Dark Side!!
Coming soon: Part 3: Return of the Jedi