I'll be honest, I can't speak to the actual educational value of ABCMouse.com. I signed up for ABCMouse.com through a reward program in order to get points, with the intention of canceling the trial before being charged. Unfortunately, what should have been a quick 5 minute cancellation process turned into 3 hours of digging and researching, because the site is rigged in such a way that cancellation is almost impossible. Based on the experiences of myself and hundreds of others, I can only conclude that this is intentional, and that ABCMouse is a fraudulent site.
First of all, it is extremely difficult to find the subscription cancellation option on the website. If you finally do, however, the site "glitches" when you try to submit the cancellation, kicking you back to the home screen. I did this about 15 times before giving up. While the account process requests your email address, there was absolutely no correspondence about charges, account registration, or account cancellation. I never received any indication that my account had actually been cancelled, leading me to keep screenshots of me canceling my account in case I had to refute recurring charges. Customer service was entirely nonexistent, as I have yet to receive any response to my emails (several months later), and all calls using the given phone number failed to connect.
Fortunately, I was never charged for the subscription after my trial ended, but I have read far too many horror stories of people who were not so lucky. Even if ABCMouse is legitimately educational, the inner workings of the business side are incredibly shady, and it's better to stay away completely. There are plenty of other educational options out there.