If it was mealy, it was probably improperly stored or grown in too warm weather. They aren't normally mealy. They're more tender and less crisp than Honeycrisp and have a pleasant texture.
You're likely not getting good McIntosh apples in your area. The texture should be similar to a typical apple, but not as crisp as Honeycrisp. A slice of McIntosh should snap if you try to bend it.
