Firstly I will say that this is a great show and one of my favourites ever. The drama was fantastic and the characters were quite well written, each with their own twisted past and story. Each with demons they needed to fight.
Practically episode was thrilling dramatic television and I would recommend this show to anyone.
However I will say that I believe this show ended at the right time. When you watch it all the way through, it feels like it really had a good ending in the right place.
To be honest, I'm not sure this show could have gone on for another 22 episodes and kept the quality.
The majority of storylines were practically resolved and any second season would have seen the writers backtrack the characters progress just to squeeze more drama out of it.
I love this show and think it's great, but I'm glad it finished when it did and that it had such a great ending.