After the excellent two Star Wars specials, this latest segment is patchy. That's not to say there's not some excellent jokes and scenes, but they don't hit as often as in previous episodes. The whole enterprise feels disjointed and while the previous two concentrated on one film each, this one flits over all six movies, using the Emperor's narration of his, Boba Fett's, Darth Vader's and a random stormtrooper's life stories as a kind of framing device.
You just feel that had it concentrated on Return of The Jedi, it would have been far stronger and maybe take another episode to cover the prequels (or just ignore them). If they couldn't think of that many humourous takes on ROTJ, no-one would have cared if they left it a year or two to think up some better stuff.