I've finally gone through all the episodes without commentary (going to listen to all the commentaries over the next few weeks, maybe bring the discs to work and treat the commentaries like podcasts). Overall, 15 was a good season. Lots of the episodes surprised me, I had largely forgotten about them and upon rewatch I really enjoyed a number of them.
Episodes I always remember liking, and still really enjoyed:
• Treehouse of Horror XIV - aside from Frinkenstein, it was a really great post-classic Halloween show. Homer as the reaper had a lot of great gags, while Bart and Milhouse freezing time is a brilliant (if unoriginal) concept. Like the commentary said, it was really easy for the animators, but I thought it lead to a lot of great sight gags.
• The President Wore Pearls - This and My Fair Laddy are some of my favorite musical episodes. Not quite up there with Sherry Bobbins, but still filled with great music and the stories are (unlike Bobbins) fairly grounded in reality.
• 'Tis the Fifteenth Season - One of my favorite Christmas episodes, if only for the many Holiday Special references and how it in itself is a commentary on holiday specials. I always love seeing Homer being infatuated by inanimate (non-food) objects.
• Simple Simpson - While it was a bit "out there", it was no different from some of the other zany episodes of the series. The animation was awesome, the story was fun and the many super hero references were great. I'd say this just might be my favorite of the season.
• Fraudcast News - Classic evil Burns, great seeing another Lisa vs. Burns story. Lots of little seen aspects of Springfield, like Channel 6 management and the Springfield Shopper get screen time. Bill & Marty have a funny scene. I even liked the old man Burns gags (lying about being 89, pushed over by an ant).
The episodes that surprised me* included: The Fat and the Furriest, I, (Annoyed Grunt)-Bot, Diatribe of a Mad Housewife, Margical History Tour, Milhouse Doesn't Live Here Anymore, The Ziff Who Came to Dinner, My Big Fat Geek Wedding, The Way We Weren't
*All of these weren't perfect, but they were a lot of fun to rewatch. Season 15 had a lot of episodes dealing with series spanning storylines including: Homer's mom (didn't list that episode above, it was alright but I thought there were some weak bits and I wasn't a big fan of the ending.. aside from the final shot which was cute), Krusty's dad, Milhouse's divorced parents, Edna/Seymour, Homer & Marge's past. It was great to see some stories resolved and continued, even if the episodes themselves weren't my favorites.
My least favorite episodes of the season would have to be:
• Co-Dependent's Day - I admit, I'm a Star Wars fan I thought a lot of the jokes were pretty funny, even if I'm a prequel defender (especially eps 2&3) and I think why I disliked this episode in part because at the time it aired Episode II was a year old, and dropped a bulk of the politics that annoyed people in TPM. So the parody was apt, but late by about four years, and didn't really apply to the second and third films. Also, Cosmic Wars? Doesn't Star Wars exist in the Simpsons universe? I'm all for parodies, but at least differentiate it a BIT more than simply being Star Wars with a different name. Seriously, a purple Yoda is the best they could do? I think the parody would have been much stronger if Cosmic Wars had more of its own identity. Then there is the main plot of the episode, which was just weak and boring. A few funny drunk Marge moments, but overall a forgettable episode.
• Bart-Mangled Banner - I read people hating on this episode in this thread, and I had completely forgotten this one, so when I got through the first act I was confused as to why people hated this one... then the final act hit and I got why. It's a pretty good episode up until the prison island. Then it just veers into wackyland with jumping from prison to the ocean to france to New York. They could have made a good episode with the town hating the Simpsons for being anti-American, and resolving that bit, but instead it was just "send them to a wacky prison!". Lame.
The rest of the episodes were good, but not great nor did they surprise me. I remembered these to be decent and they were pretty much just that upon rewatch: My Mother the Carjacker, The Regina Monologues, Today, I am a Clown, Marge vs. Singles, Seniors, Childless Couples and Teens, and Gays, Smart and Smarter, The Wandering Juvie, Catch 'Em If You Can