How long can you stay? Just a week?
I've never done one of those tours, but they are popular with many visitors to Korea, including people of Korean ethnicity born overseas. I think the itinerary is a bit like a whirlwind, and you will spend a good amount of time on a bus, so whether it is good or bad depends in part on what you like and dislike. Personally, having toured Korea independently some years ago (gradually, by train and bus, on odd weekends, etc.), I'd prefer to spend at least a day or two in each of the locations mentioned in the itinerary.
As an aside, last year I went with my oldest to the DMZ with the Koridoor/USO tour and that was just a short bus ride, but I couldn't wait to get off the bus after it was over. To be direct, some of the people on the bus were annoying to be around, even though we did enjoy the tour on the whole.
If your window of time is long enough, maybe you could spend part of your time on a group tour like this, and part doing something else? For example, you should be able to
see some fall foliage in late October, if that is of interest.
Another alternative would be to base yourself in Seoul and do short trips to the surrounding area, like
the DMZ,
Chuncheon, that kind of thing. Are you willing to drive in Korea? Or will you limit yourself to public transportation?