It is a very good stock system.
I've been shooting Remington shotguns for years (hunted with them, and used them at my last department). My home defense gun is an 870 Police, which has rifle sights. With a OEM Remington stock, I have no issue using bead sights, but rifle sights make me want to put my cheek a little higher than usual. Go a lot higher when I use my Burris scope on my slug gun. That feature for the Magpul stock is perfect for shooters that want a little different stock layout at a good price. Need to adjust length of pull... able to do that, as well. Sling attachments are also in common places, so you can run different types of setups.
That doesn't even touch on the forend, which gives a lot of versatility to a shooter. I was never a fan of Surefire forends. Running a short length of rail on the side of the forend gives me the ability to run a weapon light extremely easily. Even with no attachments, the forend feels pretty comfortable to run.
My Remington shotguns include that 870 Police, as well as two 11-87s (hunting guns). If they were two 870s, I'd probably have Magpul furniture on them. I do have a Mossberg 500, but running Hogue grips on that (it is that JIC2 model, which I wanted to keep in the pistol gripped form; pure enjoyment factor... nothing else).