My son got these about two months ago and has had happy warm feet ever since.
I had to return the first pair because they were too small. My son's feet are a little wide, but these were not long enough either. I ordered the next size up and they fit well, with a little room to grow.

We live in North Dakota and it gets well below zero here. His feet stay warm and dry even playing in deep snow with -20 degree temps (wearing regular socks). These boots don't slip off his feet when he is climbing out of deep snow and they are tall enough to keep snow from coming in over the tops. The drawstring helps a little with that too.
He says they are comfy too.

Update 11/14/2012

My son is just growing out of these. He has had them for two winters now and they have kept his feet very warm and dry. We had days last winter that got down to -60 with the wind chill and I never heard him complain about having cold feet (please keep in mind that time spent outside is VERY limited in temps like that).

The outside of the boots have held up really well. I haven't had to repair anything on them. The inside liner is still in good condition, although there are some spots where the red felt has worn off. Mostly where his heel rubs on it.

I highly recommend these boots!