Evil versions of our main protagonists aren't exactly anything new in science fiction television. I'm not sure who can claim the copyright (note to Paramount... just kidding) but maybe 'The Enemy Within' by Star Trek? Anyway, while much of this episode was predictable - I think we've all seen a 'fix Crichton' episode coming for some time, and after he was alerted to the chip in his brain the next move was obvious - there was a lot which was not, and besides it set up a neat while frustrating cliffhanger.
The three subplots of the episode were, in approximate order of importance, John's little insanity problem, repairing Moya (which is thematically linked to the first) and D'Argo's 'family problems' with Jothee and Chiana.
D'Argo is not-so-surprisingly unhappy with the state of his son, and the revelation that Jothee had cut off his own tentacles due to shame of his Luxan heritage left him shocked and heartbroken. Chiana, on the other hand, was clearly unnerved finding out that D'Argo has plans to propose to her. Chiana is someone who lives for the thrill and it wasn't hard to see how life on a farm with a husband would seem a boring prospect, and she's also wary of close ties to other people - partially burnt from being abandoned by her brother.
Really, this is a tale as old as time, the battle-worn old warrior wanting to settle down and his young girlfriend who's not had her fill of life.
Furthermore it was noteworthy to see how easily Chiana and Jothee bonded and "got along," setting up the most uncomfortable theme of the entire Farscape series. As Jothee says, "he wants to live the quiet life. I wanna live loudly." Again, this isn't strange - they are much more similar creatures than Chiana and D'Argo, and both are motivated more by a sense of practical selfishness than some code of honor. However this triangle plays out, don't expect it to be pretty.
Most of the rest of the episode consists of John and Aeryn slugging it out with Harvey with the former at a distinct disadvantage, as Harvey takes full control over John in the beginning minutes of the episode and is clearly not in the mood to be exorcised.
This is the main part of the episode which is dragging on a bit for me. The prowler chase where John is trying to get away from Aeryn may be cool visually but it lacks suspense, as at no time did I feel like John or Aeryn's continued presence on the show were seriously in danger - yes, up to and including the crash and drowning. Aeryn's funeral scene was well-done and sentimental - to the point of D'Argo giving her his sword and Rygel giving her his Dominar necklace - but John and Aeryn are the life-blood of the show almost to the extent that threatening either of them with death is as credible as threatening Bruce Wayne on Gotham. I suspect that other viewers may have found the scenes to have a different kind of impact.
The exposition looking to find a suitable donor to act as spare parts for Crichton, predictably, gives Zhaan a chance to spout off some of her sanctimonious nonsense about how the doctors have "interrupted the course of nature" by freezing the victims one microsecond before death (the horror.) That woman would make a great poster girl for a ban on abortions, stem cell research and other unsavory business. Anyway none of the others are having any of it, so - after the aforementioned car chase - it's onto the operating table!... which looks to be going all well until Scorpius shows up to murder the Diagnosan doctor just before John's speech is restored.
Farscape always has me chuckling a bit with its twisted sense of humor. I'm not sure if the scene with the doctor questioning John which memories he'd rather keep - "...important?" - was supposed to be heartbreaking, because to me it was just hilarious. Even the end, with a blubbering Crichton unable to make a coherent sound was rather laughter-inducing. I guess I'm just a cynic.
All in all, this is a thoroughly satisfying final installment of the second season delivering a lot of drama and intrigue while setting up several important points for the season to come.