Worst thing Lucas did with the prequels (besides Jar Jar
) was killing Maul at the end of Phantom. There is really no continuity between PM and AOTC. Lucas didn't kill of Vader in ANH? Why the hell did he think it would be a good idea to kill Maul in PM?
As much as I like Darth Maul, I don't think that he was the apprentice that Darth Sidious needed during the Clone Wars. Better to kill him off in battle (or not, if you've seen the animated Clone Wars ) than to have Sidious dispose of him offscreen.