V.W.
Honestly, I don't have any FIRST hand experience. I don't think they existed when mine were that little. But my SIL and her husband got one for their youngest when he was about 2. He is going on 4 this summer, and looks ready for a real bike with pedals. He is amazing on his balance bike. SO fast! His balance is perfect on it.
I highly recommend them from what I have seen with him.