On the downside, like having a baby, once you have a center you have a center. If your population changes, you still have a center and have to decide how to make it work. And money can be a downer if the company doesn't have enough of it, or isn't willing to invest enough to make it a success. Since it really represents the company, you'll want the quality to be better than your average center, and that costs money. Parents can seldom afford to pay what it really costs, so companies must count on picking up about a third of the operating cost, and all the capital costs.
Many employers subsidize lower income employees in addition.
It can get pretty pricey. Marketing, of course, is everything, even when it looks like people should be falling all over themselves to get their kids in the center. But changing your child's care provider, even when the current provider is less than wonderful, is very difficult, and when push comes to shove you may be surprised at how few people really will do it. It will make a big difference if employees are in on the planning, feel responsible for the center's success, and are made part of the marketing process. I've heard that bigger centers are easier to support.