The case part of the episode was very much "meh", and while I didn't like Jill, I didn't hate her, either. I think mostly because she was cast age-appropriately. The actress had nice chemistry with Tim and I love any opportunity for Peter backstory.

I do agree that the conversation Peter and Jill had in the car about Siegel seemed forced - more because Siegel wasn't really there that long. I think it's more guilt than affection. I did "A" and "B" happened - it's not rational, but I get it.