They are far from comprehensive and littered with adverts for Barclays Bank, BT, T-Mobile etc. but for someone who is looking for a brief overview they are great. And even better as they are free !!
I assume they can afford to give them away because of the adverts. I've had a look through a few of them, I think they are ideal if you are going somewhere for a couple of days and don't want to shell out for a book and are too lazy to go to your local library to borrow one!
Not bad for free, but there's nothing in there that isn't freely available on websites anyway. IMO - don't be lazy, and get a proper travel guide from your library...
If the "Overview" of Johannesburg and Pretoria is anything to go by I would say these are a bit dodgy, he even mentions public transport, not something you go within a 100 miles of in Johannesburg or Pretoria.