good- only one pin to look at, not a clutter of several pins to try to focus on only one, and hope its the right one. Precise yardage adjustment, if it is 34 yards you put it on 34 yards and shoot, no holding high or low with this pin or that. Smaller sight housing, and usually a round sight aperture, which seems to help me since mine will center in my peep perfectly.

now the bad-- when the animal is coming in you have to set the sight for the yardage the animal is at,, and hope it doesnt move from that yardage, you have the added movement of adjusting your sight when the game approaches,, and sometimes you dont have time to adjust if it is coming quickly. You also have to make sure you have the locking screw tight or you could bump it and move it. I think my biggest problem is getting caught up and excited when a big buck is coming in, and forget to check to see where it is at.
All in all i think it is better to use a single pin adjustabel sight, but thats just me, only you can decide if its right for you.