The scripts are those of a sub-standard sitcom. The writer attempted to copy the style of Galton and Simpson (with their blessing), not just the self-important pomposity of the character but actual situations such as trying to find a particular plastic toy in a packet of cereal to complete a set. These work to Hancock's strengths but his performance only serves to show that the script and his skills are shadows of the glory days of ten years before.
As for the performances, Tony Hancock himself is the best performer in the cast but is well past his best. Apparently, after a disastrous pilot where he was out of it on drink and pills, he was told to dry out or else. He stayed sober until the night when he used vodka to take an overdose. His delivery is clear and crisp (not always the case in his last UK work) but his timing and reactions are slow and laborious (he is also obviously using auto-cues and his eyes are constantly glancing towards them, especially during monologues). Watching a scene played between Hancock and Don Crosby you feel like checking your watch while they pick up their cues. The Australian supporting cast are not in Hancock's class and give very stilted performances.
As 'trevorwomble' says, the three episodes Hancock filmed in May and June 1968 were finally transmitted as a 90 minute TV film in Australia in 1972. Giving it the title 'special' is just a cruel irony. When Tony's brother Roger saw the show he almost begged BBC and ITV not to buy it for broadcasting in the UK. Both organisations thought it amounted to grave robbery and wouldn't touch it. The video I bought had very poor picture quality and I have learned since it was probably taken from an unauthorised rough-cut. It doesn't really matter, because I didn't want to see it twice.