This is a great tool for either introducing a new topic of US history or reviewing after the topic has already been taught. I've used it both ways and it's worked well either way. I think it would work best for ages 7+ but my son who is almost 4 will from time to time actually sit through an entire episode(although probably isn't retaining much information haha). That being said my DD who is 8 LOVES it and has asked on more than one occasion this summer to watch it, just because she enjoys the series! In my book that is a win!
My daughter & I used to watch this show years ago when it was on tv. She was about 10 years old then and loved it. I thought it was very well scripted and historically accurate (I am a teacher). When I saw the dvd recently I had to buy it for "old times sake." We recently watched a few episodes and still enjoyed it.