There are a few sweet moments here, but overall, the episode is pretty meh.
Memory Alpha has a partial summary here.
SABR Matt and I are both skeptical when it comes to the science on this one. SABR Matt thinks that the universe should've imploded once the older Molly met the younger. I, on the other hand, am a little unsure about the developmental psychology. The feral children of whom I am aware were generally separated from human society at a much younger age, so I don't know how realistic it is for a fully verbal eight-year-old girl to completely lose her speech after an extended period of isolation. But hey -- Memory Alpha claims that the writers consulted a few psychologists while they were penning this episode, so perhaps I'm wrong about the sensitive period for human language development.
As far as the story is concerned, my general reaction is - as noted above - "Eh." As I'm sure you may have noticed, I tend to prefer episodes that involve permanent consequences -- and this episode doesn't really have any, which makes the whole "Molly as a wild child" idea feel kind of pointless. There's nothing hugely wrong with the writing, but because the reset button is pressed at the very end, it's hard to get too invested.
'Tis a very average stand-alone script.
The parental acting is solid, but I can't say I was all that impressed by Michelle Krusiec's performance.
Not much to see here.