Great reputation - and the parents I know who have kids there love it. I taught Faith Formation there and found it odd that the kindergarten classroom I taught in had 28 kids in it. My kindergartener only had 17 in her public school class. I'd be pretty mad if I paid all that tuition for a class significantly larger than the local public school.
And the 2 worse behaved kids in my FF class both went to St. Matthew school, so you're not guaranteed of getting better behaved kids in your child's classes!
Overcrowding applies to St. Matthew as a parish, too. Lots of growth in South Charlotte and Union County over the last few years. Nothing can keep up.