The guy who plays Jack is such a good actor. Very compelling. Shouldn't have left the show, though. That ruined it.
It's addictive, and the character Jack grows on you, plus the kid Cody is a great addition, but when the actor playing Jack decided not to return, they should have ended it on a happy note. Also, there were way too many episodes set in the city, where Jack and Elizabeth are apart, I had no interest in those episodes at all. Finally, having Jack totally disappear towards the end of Season 4 was not a good decision, they should at least have shown what he was doing during that time. But that whole plot line was ridiculous anyway, it was like the Mounties went to war and had a slim chance of surviving. If you want a good frontier show, try Dr. Quinn instead.