On the Upside: They passed on vision trait from father to son. They ended it with the impression that Johnny and Sarah would get together. And they didn't leave us hanging on Walter's death. The fact that they used some of the supporting cast and sets from Stargate are mere bonuses.
On the downside: 'The powers behind the scenes' severely underestimated the potential of this show. The seasons were too short. The average length for a drama is 20 to 22 episodes. That is, unless it's one of those 'summer time' runs on the SyFy channel which, in my opinion, sucks. Dropping several main cast stinks of a slash in the budget. And they killed off the sheriff.
IMO- they should do another series of The Dead Zone. This time focus on JJ.
The show ran until 2007, that was 7 years ago. So, JJ would be in his teens. It would be interesting to see how a young guy deals with these abilities.