As basically everyone so far has said, this episode is very under-rated, and it really shouldn't be because it is a fantastic episode.
Previous people have mentioned how well all the plot devices come together, and this is one of the most brilliant things about the episode. The way that such insignificant things can become such an enormous part of the plot is a real credit to the writers.
This episode is full of gags, from the Antique Cans to the screen for Technical Difficulties. It is just full of laughs, and is actually one of the more funny episodes of the series. On the other side of this, the episode has some emotional bits, and they seem effortless, and tie together with everything else in the episode so well.
The character development in this episode really shines, and we get to see more of some secondary characters like Chief Wiggum and Lionel Hutz. The use of Ruth in this episode is fantastic, and she really helps balance out the character of Marge. I really think they could have used her a lot more in other episodes, and a lot more plots could be developed around her.
This episode also shows how to do great parodies without going too over the top. The parodies are there, but even if you haven't seen the original source material you can still thoroughly enjoy the episode.
Surrounded by other great episodes, this episode can sometimes be forgotten, but it shouldn't be as it is one of the better episodes.
Everything else has already been said, so I won't repeat it again. I look forward to discussing the episode more.