A week and a half after the full announcement, my brain comes charging in with this:
Each debate will be 90 minutes. So that'll be four and a half hours of debate; no ad breaks. I'm wincing at the thought. It will be astonishing if non-politicos (aka normal people) be motivated enough to watch.
Particularly daunting is the prospect of 90 minutes focused on "foreign affairs". The current mainstream issues are basically the UK's involvement in Afghanistan and the European Union. Are they going to stretch these topics over the full hour and a half? Eeek.