If you see Dar using a sword or hear the Ark mentioned, RUN. That being said, Tao was a fun character and Dar didn't need to know everything to do his job. He had a very natural and need-to know approach to life that *I* think we could all learn from. A few early episodes presented Tao as a bit of a bumbling idiot but the 2nd season interview Daniel Goddard (Dar) gave was quite accurate: Tao's concentration is what makes him trip over. He's cerebral and Jackson (Raine aka Tao) got that.
The First Sorceress grew into an actual caring and very confused being, once she got her memories back. At Which Point the AO became a sanctimonious prick. The second actor to play 'the sorceress' actually plays a different character, not just the same character a different way. The Black apperition is a mystery that I will not spoil and Arina starts out a mystery, is revealed as a mercenary and does a double-take. Watch any episode Ghosts of the Forest onward to see the double meaning in that.
Marc Singer was the complete failure...so a lot of people say. I personally think the producers re-did the focus and purpose of the episodes and the characters and lost what made the show great. THe balance of nature, the mulit-facted and multi-dimensional characteristics of both animals and people. It rocked for exactly two years!