I am going to try to answer this question Seriously when I haven't in the past and instead posted a list of fanfics.
Assumes serious face.
Fair Warning: For new fans, I don't recommend watching anything outside of Season 1, Season 2 and from Season 3: "Double Cross," "The Guardian," "Dead Man Sliding" and that's pretty much it. According to SLIDERS expert Temporal Flux, co-creator Tracy Torme gave up on the show in Season 3 and stopped going to the set after "Dead Man Sliding." The other co-creator, Robert K. Weiss, had left after Season 1.
I'd suggest reading Wikipedia entries to finish out Seasons 3 - 5.
Gems Throughout: Season 4 has some great episodes. "Prophets and Loss" is a throwback to 80s style television formula but done with incredible craft and passion: there's one scene where the sliders are interrogated and it seems to happen in real-time. "Virtual Slide" has some neat perceptual tricks and deft twists of plot. "World Killer" is a minor masterpiece of SLIDERS.
"The Alternateville Horror" has some brilliant touches of humour and cinematography and staging. "Slidecage" has some spectacular hard sci-fi concepts and one of the finest visual realizations of the series. "Slide By Wire" is an impressive, well-paced tech thriller. "Way Out West" is a very amusing Western spoof.
Seven standouts in a season of 22 isn't great.
Diminishing Returns: In Season 5, "The Unstuck Man" is a clumsy, witless, joyless hour, but there's something impressive in writing Jerry O'Connell out of the show with a note-perfect impersonator. "Applied Physics" is a brilliant exploration of the new situation and a moral crucible for the new slider, Dr. Diana Davis, but the threads it sets up are unfortunately discarded in the rest of the season.
"New Gods For Old" is a magnificent exploration of free will, individuality, collectivism and community but sadly destroys what "Applied Physics" set up. "A Current Affair" is really lighthearted and funny. "The Return of Maggie Beckett" is one of the best scripts ever written for the show. And that's it. Four standouts and one interesting failure is pretty sad for a season of 18 episodes.
Setbound and Bottled: The show changes in ways that aren't to its benefit. Season 3 moved production to Los Angeles and proceeded to set the show there and make no effort to use night filming, stock footage, lighting and colour processing to maintain the San Francisco setting, declaring that the sliders would now slide to LA from now on (aside from two episodes in Season 3 and one in Season 4 that insisted on San Francisco). The show's use of backlots and outdoor studio sets eviscerated the indie film look achieved in Seasons 1 - 2 with location filming.
Should've Travelled Light: According to Temporal Flux, the Season 1 - 2 team had very bare, empty soundstages that could be reconfigured into any interior. If they needed Quinn's basement, they wheeled in the blackboard, the sliding coils, the worktable and the furniture into any soundstage and that would be the basement. If they needed a courtroom, they rented a judge's bench, a jury box, the tables and some chairs. For a hotel room, they'd put up false walls and windows, bring in some beds and put a TV on a dresser. Then they'd pack all that away and bring out what they needed for the next set.
Police Stations: In contrast, the Season 3 team built an expensive cave set that ate up their money with rental costs and maintenance and forced them to include it in episode after episode whether the story called for a cave or not. In Season 4, the production built a vast hotel set, the Chandler, with its lavishly decorated halls and bedrooms consuming the money in rental fees and upkeep and forcing nearly every episode to be set in the hotel whether the plot needed the hotel or not. And they kept it for Season 5. The Season 3 - 5 producers were veterans of cop shows which maintain a police station set; they were indifferent to how SLIDERS needed a different approach.
Beige Curtains: Visually, the show takes a nosedive. Season 3's standing sets are livened up by high contrast and high saturation and a good amount of location filming in LA despite the cave set. Season 4, however, is largely studio-bound and it's a bleak, dim, gray, dull looking show. Season 5 maintains the same look and starts filming in the Hill Valley Square from BACK TO THE FUTURE and it looks ridiculous.
No Review: There's also the sense that the script editors and producers are not performing quality control. Starting in Season 3, characters are often not introduced by names and reviewers have had to check credits and scripts to know how to refer to the guest-characters. Exposition is given in the most artless fashion through a guest-character, Diggs, dumping the information onto the sliders through inane dialogue. Actors misdeliver lines and see those takes aired. Characters also behave in shockingly sociopathic ways and the writers and at times actors are totally indifferent to how bad it makes them look.
Sociopaths: We have Quinn falling in love with an unconscious woman in "Dragonslide," Quinn flirting with Wade's sister when Wade is despondent in "Season's Greedings," Quinn flirting with a married woman in "The Exodus Part I," Quinn refusing to let his friends go back to their home Earth for no clear reason in "The Exodus Part II," Quinn tricking his terrified friends into thinking he's being electrocuted in "Sole Survivors," Quinn abandoning the sliders in "Slither," Quinn having no interest in saving Wade from a rape camp in "Mother and Child," Quinn having no interest in saving his mother in "Revelations" -- some of which is poor writing and some of which is the actor mis-performing the scripted dialogue or adding his own subtext to scenes -- and these incorrect takes being aired anyway.
Disavowed: We have a series-ending cliffhanger despite the show's producers knowing full well that there wouldn't be a sixth season.
SLIDERS was, after Season 2, abandoned by its original creators, denigrated by its gradually departing cast and disavowed by those involved. Seasons 3 - 5 are, on the whole, not an enjoyable, professional product. Whatever fanbase the show has is entirely due to the first 22 episodes and a few scattered throughout the last three seasons. In the years to come, the lead producer for Seasons 3 - 5, David Peckinpah, died and there was much rejoicing in this community. His family posted on the now defunct Sci-Fi Channel forum and defended their family patriarch, protesting the way SLIDERS fans reveled in their loss.
Binge: On the IMDB boards (also defunct), one of Peckinpah's sons explained: Peckinpah had been a good father, a devoted family man and a recovered drug addict who had been sober for 20 years in order to focus on his wife and children. In 1994, Peckinpah's 16 year old son, Garrett, died suddenly from bacterial meningitis. Peckinpah fell apart and fell back into heroin and cocaine.
Peckinpah had a development deal with Universal and was assigned to SLIDERS in Season 3. Peckinpah's grief and addiction made it impossible for him to properly oversee commissioning stories and reviewing scripts or ensure actors performed their lines. "The Exodus" two parter of Season 3 was commissioned not because it was a good story, but because it allowed Peckinpah to hire musician Roger Daltrey for a guest-role and devote two weeks to an on-set rock concert with Roger Daltrey's band. Filming the episode was something to do between performances and binge drinking sessions.
Addict: Peckinpah was bitter and angry towards anyone who questioned or protested his attitude, firing John Rhys-Davies off the show and driving Sabrina Lloyd to quit as well. He had no concern for the content he was producing and it showed. After SLIDERS, he moved from LA to Vancouver, presumably to develop new projects but really to indulge his addiction. Without his family and friends to watch him, Peckinpah overdosed and died, so Seasons 3 - 5 are simply a symptom of a deeply troubled human being and his gradual self-destruction. Season 3 is cocaine, a superficially thrilling but emotionally dead experience. Season 4 - 5 are heroin, a sedating, lifeless endeavour.
Fans view Peckinpah as a demonic monstrosity. He was just a man. Broken and lost. Peckinpah killed himself and in the long process to do so, he took SLIDERS down with him. He died longing for his son, he died in infamy, and he died alone.
Restoration: Anyway. If you do watch the show past Season 2 and somehow get to the end of Season 5, consider reading the "Slide Effects" screenplay which was what Tracy Torme would have liked to happen next in SLIDERS. https://earthprime.com/etcetera/slide-effects-2