are you talking about the baby doll or the big $100 one?
the baby doll is very nicely made, and if your daughter doesnt care about it "doing" anything, and you dont mind $50, it is cute. we made it a big deal, and my 3 year old takes care of that doll differently than her others. but its still just a baby doll. we only bought one outfit, but the accessories are def not worth the $$$. if she likes taking care of the doll, get the baby doll. or you might consider a toddler doll, they are $50 separately at the store.
if you are taking about the $100 dolls, your daughter is way too young. they market them to 8+ year olds, and the characters are about 10 years old. the outfits and accessories are completely overpriced, but the doll really is special. and its not just about the doll. the books give you a character. my 6 year old sat through the whole kanani book in one night(no pics, chapter book). its neat that each doll has a different personality. the other dolls that arent characters are cute because you can get one that looks like you, down to braces or wheelchairs. you can get them in outfits of your favorite things to do, its just amazing, but expensive.
we got our 6 year old kanani, the girl of the year, for her birthday. she was looking at the magazine at 5. we bought just one extra outfit. you can get the dollie and me outfits all the time on zulily. micheals has doll beds that look just like the AG ones. you dont have to go crazy.
i would strongly caution against getting the doll too young, i think 6 was perfect. otherwise, they dont cherish or have it to look forward to, and they dont understand how special it is. it would be cute to get the baby now, to kinda work up to the big one when she is older. or just wait and get a cheaper baby doll. and if she likes baby dolls, she may never like the big AG dolls, they are a friend, not a baby. good luck, my daughters kanani still has her hair ok(i really tried to steer her towards picking a straight haired one, but it didnt work)