my kids were teens by the time i read it and i had already converted to a gentle approach, so it was pretty easy for me to incorporate the big ideas. not sure how that would have looked had i read that book first and my kids were little....
it's been awhile, but what i found most helpful in UP was that it explained so much of my frustration with my own childhood and the way i was parented. being able to give that a name and let it go has made me a better person.
final thought: if you go UP, keep in mind that you won't be able to do it perfectly. no one can. we are all in process. so be gentle with yourself as you practice gentleness with your little ones.