You can really learn a lot about the background things of the show and the amount of work the staff put in to the show, even back then when they had a small amount of people and limited budgets. Like special guests being cautious on leaving there real name on the credits and the staff having difficulty with copy-right material.
I've heard most of the commentry, and I think the back story to how they made "War of the Simpsons" is pretty interesting, and how they re-wrote the plot, and how Nelson's "Haw-Haw" came about.
Also Willie ending up Scottish, where he could have been Spanish!