As a stock phone the evo 4G is just about at the end of the line. I love my OG evo, but I'm rooted. I can change it as I see fit.
Development for this phone was huge from the beginning, so the root community is strong still.
If your kids have strong computer or tech skills, they may enjoy the root side of the evo for a little while.
Ard is correct tho, if you're going to buy new phones at this point in time, you "may" want to get a newer device.
It killed me a little bit to post that last line.