I will just start by saying that this episode is perfectly fine. But looking at the reviews, and the score, for this episode, I can see this one didn't sit well with the fans.
Is it a rehash of an earlier episodes? Well yes, it is a bit. It does have quite a lot of similarities to "The Other Jackie" in that it features a crazy Jim love interest, but we are in series 6 now. There are only so many plots you can do with a family eating dinner on a Friday Night. And I feel this episode's plot was just different enough to not feel like a total rehash.
This episode wasn't super amazing, but it sure had its moments. The scene where Jim is rambling on about a "very round marble" had me in fits, and Jim's dance in order to entice Gibi out of the bathroom in the cream tea place was also another shining moment.
This episode wasn't one of the best by any means, but it's far from the worst. It didn't do anything really wrong, and I don't see why this of all episodes is the least favourite amongst the fans. 7/10.