I bought one about a year ago for my dad. He had a very hard time getting his rifle steady, and to be consistently accurate.
It took alot of playing with it to find the exact right way to set it up for him. But, once we got it right, it has allowed him to be very accurate.
I have tried it a few times myself. If you get it solid to the ground and balanced it is very steady.
With the shoulder strap it is not much of a chore to take with you anywhere.
I've used it more as a gun vise. Such as leveling a scope or cleaning a gun.