Li'l TI has one (he'll be 3 in Feb) and loves it. One nice thing about striders is that you can adjust the seat and handlebar height, making them somewhat scalable. They're well made (dude is not easy on his) and affordable too.
Agree with Buck and jinx below - go with a small bike so D4 can learn how to balance. She'll outgrow it, but when she does she'll be ready for a big girl bike.
