I finally finished the 12-week preseason program! They've decided to add 4 weeks on to the preseason and also the postseason programs, and the extra 4 weeks show up, but I can't access them yet so I'm assuming they aren't ready to be released. Getting through the program definitely took me more than 12 weeks due to going to AK for sheep season, having my wife in and out of the hospital for a few months with hyperemisis (all-day morning sickness that just doesn't go away and can lead to severe dehydration and malnutrition), hunting season itself, and getting sick myself 2 different times...but I wanted to finish no matter what. I think it really is a good, well-thought out program. One thing Dustin (the founder) mentioned in an email is that the program won't give you 'glamour' muscles, which it doesn't. It pushes you in the areas you need in order to push yourself further in the mountains. Most of all, I think it really helps you develop that mental edge to not give up when things get tough and you're worn out. What I used to call a 'hard' workout was really not that hard...some of these workouts will really test you. Some days it's all you can do to make it though, but this is one of the best ways to stretch yourself and increase your own mental toughness. I remember some of the hardest workouts (for me anyway) being the Goat and the Lyle; the Ibex was really good as well.
When they announced the offseason program I honestly didn't plan on signing up for it, but now I'm considering it

One of the things I really like about the workouts is the structure. They even have different 'levels' of difficulty for some of the workouts depending on how good of shape you're in and how much you want to push yourself...but don't think you'll get off much easier if you do beginner level of weight/difficulty/etc, you will still be borderline exhausted by the end if you really give it your all and do things as they prescribe.
To anyone on the fence about this program, I'd say go for it. It's an investment in yourself. Just forego a gear upgrade that may only save a couple ounces, and start MTNTOUGH so that you can lose a few to possibly several pounds off your frame

Your joints and back will thank you. Even if you get through it and don't like it after it's all said and done, you WILL be in good shape for hunting season. I plan to start over from week one in late april/may and be wrapping up in time to go to AK for sheep and then start bow hunting at home.