This review contains spoilers.
After Magnum was brought back to life in 'Infinity and Jelly Doughnuts', this episode serves to start putting things back to normal. Well, by the end at least – it takes a wayward route to get there. After the seriousness of 'Infinity...' and much of 'Limbo' before it, 'Pleasure Principal' calms things down by being a gentle comedy, and personally I think it works.
I am surprised that this episode isn't held in higher regard – although not unpopular, it often seems overlooked, but I personally think it is really good.
Magnum and Higgins effectively swapping places is a novel – and overdue – plot device, and I think it works well. Yes it could be argued that more could have been done with the premise, but even so I think it is pulled off quite well, and works for its subtlety.
It is amusing to see Magnum dressed smartly and acting reserved, while Higgins effectively becomes all of the things he dislikes about Magnum.
There is a 'main plot' in there, about the woman that Higgins is secretly meeting at dance clubs supposedly being up to no good and planning to rip him off, but for much of the episode, that main thread is very much incidental, as we instead get a number of scenes showcasing Magnum and Higgins' role reversal.
I particularly like the afternoon tea scene between Magnum and Agatha – a near replica of many Higgins / Agatha scenes from previous episodes, just with Magnum in Higgins' place. Magnum even has Higgins-like dialogue and speaks with a faint British accent – it is explained at the end of the episode that after such a trauma as Magnum's (near) death, people involved sometimes subconsciously start imitating those close to them; but beyond that, I think the director was just having fun and not taking it too seriously.
Only in the final ten minutes or so do the 'main' plot, regarding Higgins' mysterious woman friend, kick in, and it turns out to be a series of explainable incidents and misunderstandings. Although I love a good action-adventure ep of MPI, at the same time I like that not every episode has to end in an explosive shootout, and like this episode all the more for not going that route.
I remembered this episode – which, like most season eight episodes, I haven't seen for quite a while until coming to review them – as being a solid 10. I'll admit, it isn't quite that, and it does have its sillier moments (I wasn't sure about the exploding Mac!). But personally I like this one enough to give it a very decent 9.5.