This is by far my favourite pack and I haven't gotten past infant stage yet! It fills in some of the toddler things from Sims 2 and Sims 3 that I felt were missing like teaching toddlers to talk and walk - I know we don't get that, but all the infant milestones mean that toddlers can already talk and walk so it doesn't feel like it is missing anymore. My infant has taken almost all of her long lifespan to get the milestones, so I feel sorry for those who play on normal and short, there's no way they would experience everything.
The family interactions are great, too, and something that has also been missing. My sim parents became "close" and earned the romantic trait due to their interactions. The self-discovery traits do come up often, perhaps too often, as I have to keep turning down the clumsy trait every time my athletic sim slips on the treadmill :D !
It is (for me) far less buggy than anything else I've downloaded in Sims 4. The only bug I've had is that sometimes the parents get stuck with the infant, but a quick reset has solved that every time.
The reason I couldn't give this a 10 is because I'm not a fan of the world. Everything is far too spread out and it's hard to work out what is real and what is fake (most is fake). My sim parents keep getting a want to use a bush for woohoo, but I haven't found one close enough to the house to use. I do like the library though, it has something for everyone, and I'm waiting until my kids are old enough before trying out the community centre.