The major issue is underestimating the average voter's mentality. People will vote reform based on the headline promises, and not care about the other policies until it affects them.
Reminds me of when we were offered a pay rise at work in exchange for more flexibility to our hours. The first day this kicked in one of the people who was happy to vote yes due to the pay rise was complaining the new flexibility rules had negatively affected them!
If they get in I fully expect people crying their house value has cratered cos their mate Nige is fracking nearby.