Some of the costumes and sets look a little cheap to me, especially compared to those on shows that air today (although to be fair, I would guess that the budget on a show like Game of Thrones dwarfs [seriously, no pun intended--I hate puns] the budget that Farscape had to work with). But like you're saying, the strength of this show is in its characters and their development, not so much in its visual effects and art direction.
On a related note, after all the shows in the last decade or so where the protagonists have been, if not The Bad Guys, then at least bad guys, I've found it refreshing to watch a show where I actually like and root whole-heartedly for the main characters. Though I can appreciate that there have been some great shows lead by anti-heroes, I think that trope has become overused. Series like Farscape should serve as a reminder to show runners that heroes don't have to be boring and that characters can be flawed but still lovable.