I watched these series at the time and had almost forgotten them. It was an eye-opener to watch them again. I hadn't really noticed the BBC dumbing down but when you watch these programmes you realise that it is going on.
The most striking thing is that in these series there is no 5-minute explanation of what you might've missed last week, or of what to expect next week or constant repetition of who everyone is and what they've just told you. In these half-hour programmes, you really do get 30 minutes of material.
Apart from that, these 3 series are very informative, well presented and a fascinating insight into the past. Some of the techniques are worth trying at home or on the allotment, as well. Well worth the money, although I see the price has gone up since I bought them.