These shows were great in the 60s when I first watched them aged 6 or 7 and they're still great. I still recall the sheer thrill of watching Thunderbirds (sadly not in this set, but shown often on TV over the years) on my parents' black and white TV. Even without colour the excitement generated by the music and the action was terrific. Quite a step up from Andy Pandy, my previous favourite.
It made me laugh recently when I heard a BBC executive say something like "kids today like more jeopardy in their TV viewing than in days gone by". You can't get more jeopardy than in a Gerry Anderson show. For goodness sake, Captain Scarlet actually died at the end of every show, usually in a fire or crushed by a boulder. In Dr Who hardly anyone ever perishes - they're too busy showing they're in touch with their emotions.
One observation from a 21st Century perspective: I think Joe 90's dad would get a call from social services for sending his son out on secret missions against armed and dangerous criminals. Didn't bother me in 1969 though; I still have my Joe 90 membership card somewhere