Depends on what you feed.

Corn around here causes far more problems than it cures. A lot of people buy the cheap corn, and some of it has toxins in it like aflatoxin. Deer hunters routinely kill more quail around here than quail hunters do because of buying low quality corn, storing improperly, and then feeding. The corn becomes tainted with aflatoxin and fumonison and the animals eat it. It can harm any animal that eats it, but I have long thought it did a lot of damage to the quail and turkey populations here.

Another thing to consider is this: The animals you are feeding are prey animals. This makes feeders attract predatory animals. Hawks and owls watch feeders all the time, and they get used to the timing. Coyotes and bobcats also like to hang around the general area of a feeder to see if they can catch an easy meal.

I have a feeder, and I use a 50/50 corn/protein blend. I get the corn from a feed store that has been properly tested and handled, and I ensure it is handled properly and stays dry until the feeder spreads it. The feeder is a good one, and it is water proof. It feeds around the house, so the effects of predators is somewhat lessened. I routinely see all forms of wildlife, and have had in the past up to 60 deer a night coming up to feed. Rabbits, turkeys and squirrels are common. By the time the coons come out at night, the food is gone, and the feeder is coon proof, so they don't get much benefit.