I just tried my buddy's GP 100 .22 tonight and we did some bowling pin shooting, (also tested a prototype speed loader for it).
He just got it last weekend, the action is tight and it looks great. The trigger is not bad for a new gun, I'm sure it will smooth out with use.
We shot a few hundred rounds with the Ruger and found we were having occasional misfires, about 1 in 30. I shot just as many rounds with both of my 617's with the same ammo and had no misfires. After comparing the spent rounds, we noticed that the Ruger was hitting near the outer edge of the cartridge, actually making a sharp burr on the edge of the spent brass.
We also noticed some sharp edges on the frame, crane and hammer, might cause some lost skin someday.
He is going clean and inspect but I'm afraid he may have to send it back for firing pin repair.
As far as a comparison to the 617, the frame is a little bigger (more like an L frame S&W), the balance is good because it has no full lug under the barrel. It's not fair to compare triggers yet, my S&W's have reduced trigger springs and have many thousands of action smoothing rounds through them. I prefer the black partridge front sights over the green fiber optic, also noticed no glare reducing serrations on the GP rear sight.
Otherwise, I like the gun and I would like to add one to my collection.