There you have a show that has it all - a great idea, a wonderful cast, plenty of room to maneuver - and at the end of the first season it all falls apart. Season one is different and almost makes it into the cult sci-fi category and then it seems that the producers cotton on to the fact that they have something special there and 'commercialize' the whole business. If you think season two is hard to watch, season three is a pain. Gone are all the promises of originality and everything that made the show special.
If you loved 'Highway to Heaven' you really gonna enjoy the last third of season one and the remaining episodes - if you look for something different: Keep looking.