I thought tonight's episode was terrific. It had a coherent plot with basically one single story line. Lots of guest stars who weren't just superfluous but actually added something. Lots of great jokes. Relavence to current events. And Homer wasn't THAT stupid (hey, I can sympathize with being disoriented by a roundabout). But then the Simpsons "vacation" episodes are usally pretty good (Africa excepted). My favorite jokes: Henry Higgins and Col. Pickering kissing, and the London Eye Pod transforming into a 007 aquavehicle. And what about Homer's Step-sister...WEIRD! Dan's female British version of Homer's voice was really funny.
When Mr. Burns' $1000 bill flew through the air and landed in Bart's room, that was a little too similar to Homer's $20 bill which landed in Bart's possession in the Junior Campers episode.
I think it's safe to say this is the best episode so far this year. (Sorry, I missed the episode with Homer's mother)