It offers a unique take on fantasy meets reality
Someone already mentioned Crichton's personality morph to what they considered overacting, but many fans saw as a rational character evolution.
In fact, Farscape offers a unique take on just about all of the scifi conventions, and as most've said, pretty much gets going around A Bug's Life
. But the story arcs never reach the heights of, say, a Babylon 5, when it comes to complexity.
Also, each season is pretty different from what went before (what the creators likened to a 'different flavor'), so a lot of viewers became put off when the flavor continued changing past the point they found sweetest.
It can get pretty "out there" at times, but even the weak ones have worthwhile scenes (Jeremiah Crichton starts with 5 minutes of valuable character interaction, and Crichton and D'Argo later share a decent moment, although in fairness even the devoted find this one mostly shite).