Not much new that I can say that has not been written above. I have owned a bunch of them, from .243 to .338 Win Mag. I had two of the .338s. I have one in .270 right now.
Pro:
accurate
dependable (when maintained!!!)
design reduces recoil from big boomers
Con:
heavy
fiddly magazine (in two pieces!)
I bought one (used) in .308 Win for a buddy of mine who wanted a semi for deer hunting. I scoped it and sighted it in for him, and was quite pleased with the gun. He fired one round, which did not eject, and was mad as hell at me about the gun>>>>>>> turned out the gas piston was filthy dirty and that was the problem. A thorough cleaning by my smith and all was well.
Speaking of my smith, he had the same thing happen to him last year. He had done his initial sighting in with Berdan primed Czech hard point .308 ammo, and had cleaned the BARREL etc. First shot worked, and then no ejection for a follow-up shot on a buck going Mach II in front of the hounds. You can imagine the fun the guys had in HIS hunt camp when it turned out that a GUNSMITH had a malfunction because his gun was dirty!!!!!
So if you are a non-technical person like myself, who has no idea whether you need to install the scope adjustment fluid before or after you put the break-free in the gas piston filler hole, then you might want to think about a rifle that is not a semi.....
Doug