I really like the idea of having a bunch of litmus tests like this that you can rate just about any business concept against. I think far too often people get married to the first "million dollar idea" that pops into their head and they almost all skip doing this type of analysis. This list is excellent and could save someone years of lost time.
There are some things that I wish I had done differently for sure. Namely looking at competitor price points and understanding the impact that would have on the business.