I’ve not watched the final episode yet, but I agree with some of the above comments.
The series was a mish-mash of ideas that didn’t really hang together very well.
In the same way that Top Gear presenters like to do, Kevin McCloud seemed too keen to display a high level of ignorance. There was too much “cocking about”.
In my view, Kevin McCloud’s reputation and credibility from Grand Designs have been damaged by it. (Strictly Come Dancing/eating bugs in a jungle next year?)
Fred Dibnah did this sort of thing far better, as do James May (away from Top Gear) and Hugh Fearnley-Whittingstall, in their different areas.