Defending against the stereotypes thing...
D'Argo is really only "the angry, angry warrior" in the early part of the first season. After episodes like "Back and Back...", "TGIFA," and "They've Got a Secret," where his character gets opened up, he starts speaking more quietly as he comes slowly to have to rely on and trust the people around him, and as they come to figure him out and understand him more. That's not stereotyping, or switching writers... that was planned character development. Remember also that D'Argo reacts in anger to stress and personal frustration. A certain D'Argo-related story arc starting in late season two and running through early season three has D'Argo being more growly and screaming and angry than I've ever seen him in the show's history. D'Argo is in character as angry... they don't play him as a stereotype.
John was never portrayed as "the big blustery American" (in fact, if anything, he more closely fits that description now, with his gun-toting and throwing people up against walls more than he did in season one). He was the somewhat clueless, completely lost guy stuck in the middle of everything that any of us would be, stranded in an alien environment. He was, in a sense, the unspoiled innocent to a certain extent (up until his encounter with Scorpius, of course).
Aeryn's character was a lot more complex than "strong yet vulnerable." In fact, now I'd criticize that her character gets cheapened and flattened by a certain arc she's been stuck in lately involving another character on the show (judiciously avoiding spoilers here).
Zhaan's "nice but strong" side was only a small part of her. Zhaan could be truly nasty at times. Remember the red-eyed Zhaan? Remember hacking off Pilot's arm? Remember her "dark side?" But beyond that, Zhaan was already in the first season a presence, more than any other, that helped the other, more abrasive characters gel together. Her character and her role as the spiritual heart of the crew was far more complex than just the "nice strong one."
While Rygel gets used or abused as comic relief a bit too often at times, watching season one should already let you know there's more to him than three stomachs that never seem to fill up. He's a brilliant negotiator ("Exodus to Genesis"), capable of incredible treachery both for the benefit of the crew ("The Flax") and turning against them ("Family Ties"). He's been a sovereign who has ruled billions of subjects, and has been a tortured prisoner for nearly a century and a half, and he still carries his demons with him ("PK Tech Girl," "Durka Returns"). Even though Kemper is probably his most vocal advocate amongst the writers, Rygel was being handled very admirably before he "took charge," as it were.
I'm an avid defender of season one. Crichton is at his most approachable and understandable as a character then, it has some of the most incredible and wonderful stand-alone episodes, and plenty of humor.