I've been using Pimsleur the last week so far. Since the speed appears to be a native pace, that's good. Since it's spaced repetition, that's good. So far, like others, I just go through a lesson a day. If I miss way to much on the first pronunciation, I'll just repeat that lesson soon afterwards that day. I cannot see any reason to sit through the entire course more than once, nor take a year to do it.
Seriously, I think it's best to use on the move. Walk around town listening to it and doing the lesson. Be distracted. If you can reply correctly while walking into a McDonalds, you're mind is getting a better workout. Besides, isn't that how you normally talk, when doing something else at the same time?
My justification is getting a grasp of basics so that I can make out a bit more of the Japanese audio rips I'm doing (Marimoe podcast, Tiger and Dragon, Prince of Tennis, Full Metal Alchemist, Some movies, etc.) Granted, I get the benefit of immersion by being in Japan. However, as many here know, it's very easy to stay English only in Japan (and many other countries) so I do have to force the issue even here.
PS: yes, don't buy it. WAY too expensive