Search "squirrel .17 hmr", and you will find one I shot at 50 yards and its pretty graphic, you can see clear through the torso. One limb was severed, and like 7 feet away from the rest of him. It easily has the accuracy to head shot them at that range and out to 150 if the rifle and shooter are capable.
I've dropped squirrels on the move at 150+ yards. So I would put it's minute of stationary squirrel at 200-250 yards on a calm day to dead still morning, but out to 150 is where it really shines. Less if it's windy but inside 100 yards I've not found it to affect me much. Just hold over an inch or less up wind on a mildly windy day depending on wind and distance. Inside 75 yards even on a windy day its going to be a laser.
I wouldn't own one if I lived in the Midwest where the wind is violent, but here in Georgia where it's usually not very windy I love mine. I can shoot better than half inch groups at 100 for as long as I do my part with my used $200 marlin. This translates to having the potential to make a dime sized or better group at 150 yards if conditions are perfect and I do my part... With a rimfire.
I have seen the external and terminal ballistics of the 17 grain v-max from 20-150 yards. Impressive, devastating, and rediculously accurate for its diminutive size is my opinion. If your just hunting with it. You can expect nearly as many animals as bullets, but it's so much fun to target shoot with and ammo is reasonable and usually available.
I expect it to stay around a while.