This is such an excellent high chair, I'm glad I spent a little extra money to have this for my first child and all my children afterwards. It is easy to adjust the height of the seat. My baby fit fine in the chair from 6 months and up. I wouldn't invest in the extra baby cushion inserts, seems like a waste of money when the baby can sit up just fine in the chair without them.
Since is it made of solid wood and the legs are spread far apart it is not easy to tip over. My daughter has not been able to rock it from side-to-side at all. If she gets her feet up against something, she can push herself back (she has never managed to tip it all the way back, however), but that is easily avoided by not putting it next to anything that she can push her feet off of.
It is so easy to clean, which is one of the biggest pluses to me. All the other baby chairs have all this padding and cloth coverings that food can get stuck in everywhere and rot. This has only a small cloth cover over the seat that is easily wiped off and there aren't that many crevices for food to hide out anywhere.
One other great thing is it looks almost like a regular chair, and it's NOT a gaudy, ugly, obnoxious high chair that screams to everyone who comes into your dining area or kitchen that you have a baby. It matches great with our other hardwood chairs and it is very understated and functional and safe. I would highly recommend this to anyone. Pay the extra money and you won't regret it.
Basically, I love this chair and think it is completely worth the investment.