Season 8 of this show had continued the generally high standard thus far, but seemed to have more plots that were triggered by a big event outside of the (comparatively) normal world of the Simpson family. In the ninth season there is still a good chunk of this, where Homer joins the Naval reserves, or the kids get trapped on an island, but generally it is not such extreme things such as we saw in the eighth. Instead we have more which are more based in character or in smaller events; this is not to say that it is not larger than life or in the realm of the fictional, because of course it is, but just that the plots seems a bit more balanced and even if they lead to bigger things, they do not jump right into them from the very start.
Crucially they remain funny, with lots of generally funny material as well as asides. I am not sure if it is real or just my perception, but there did appear to be a lot more guest voices than previous seasons. This mostly works because whether they play themselves or not, they generally feel like being done in the service of a joke, or because the person worked well – none of them really feel like they are in an episode because the producers just needed a name to draw in ratings (which perhaps is more the case with later seasons). Animation remains very good (and still looks so, 18 years later) and of course the voice work is generally very strong, with good sense of character and timing.
It has been quite a few years since I last watched these episodes, although when I did watch them they were on either Channel 4 or Sky very frequently, so there is an element of knowing the episodes inside out already, but otherwise it remains fresh and funny season.