How do they work? Are they worth it? They seem cool, but nobody that I know has one. What are the pros and cons?

I absolutly love mine. I am a terrible judge of yardage. This takes the guess work out of the shot for me and I can concentrate on my form. I shoot the model made by Cobra. With my bow its dead on from under the tree out to about 30 yards.

Treestand sights are an excellent choice if that is you primary style of hunting. They allow you to aim dead on from in tight to around 25-30 yds or so. Many are usable for ground hunting out to those distnaces as well.

Except for hills!!

Generally speaking you set the moving pin for 20 yards on the ground. then climb a tree and you should be able to shoot from the tree out to about 27- 30 yards depending on how fast your arrow is. That is if your form is good and you know how to shoot from an elevated position.

Downside to them is that they have moving parts and with moving parts comes another possible breakdown and most have a slight buzz when the arrow is released. I have used a couple of different ones and the slight buzz hasn't affected the outcome of the shot at all.

If you are going to shoot mainly from a tree stand then you cant beat them from 0 to 30-35 yards depending on how fast your bow shoots. The Trophy Ridge Mantis has a lock on the sight to lock it down for transporting, traveling and for shooting from the ground. When you get up up in your stand just turn a little knob and unlock it, works great.

Not true kimosabee.I can shoot just fine out of stand on hills that go up or down being as you sight in from 20 yards on level ground so if you are on a steep hill thats going up and the deer are almost level they still work great and if the hill goes down its still dead on and much easier to shoot than guessing what a regular pin and physics will do to your arrow.

Can anyone recommend a good one?

I do believe that I will be buying the Vital Bow Gear pen. sight

Savage makes a good pendulum, they aredead quiet.

It works fine on hills. The penedulum swings to make up for any angle.I hunt in deep hollers in theOzarks never missed a shot on a hill, since Ive been using the penedulum.