One thing that niggled us from this guide was that although there is a nice, clean layout to this guide, there could have been a lot more diagrams and images to support the steps described. Sure, the diagrams that are included in the guide are definitely clear and high quality, but there are just not enough of them!
You could get by without them we feel, but there would be no harm in including more for the visual types of learners.
The other thing that we were not too sure about was whether doing it all for under $200 is possible. The website makes such claims but we felt that in order to really hit that mark you would have to still tale the time to find the best deals...so whilst not impossible, certainly not a guarantee.
Finally, the creation of your own solar panels and wind turbines was quite technical and we felt that it was a little tricky to do from scratch at first (but the tip on finding cheap/free solar panels made up for this!). I can imagine that some people would not get off the starting block, particularly if they have no experience in DIY skills and have little inclination to do some practical work.
Whilst that sounds like an obvious statement, there will likely be a few people who buy this guide who have no intention or ability to apply the steps, so this is worth mentioning to the "less initiated".