It's great to see what some of the fellow British reviewers have said about this show. UFO, in my opinion, does rank as the best British sci-fi televsion series to date. These later episodes do tend to differ greatly from the earlier ones with slightly more plot and action pieces which of course is great. The earlier episodes, which are of just as higher standard, tend to be a little more character driven so it's great to see that the series overall demonstrates a nice blend of action and character driven storylines. The imagination here is also stunning. Much has been written about the purple wigs and who cares why they have them; they look awesome as do the girls that wear them but that's another story! The design work on the show including it's vehicles and special effects is also of the same high standard including SID, the talking satellite with a cool, polished voice.
In reading some of the american reviews I was stunned to see some people attacking this show for it so so-called 'low budget special effects' or 'Thunderbirds-style special effects'. The show was indeed produced by the very same team that produced Thunderbirds and the effects are stunning. Even when Thunderbirds and Stingray were made in the mid 60's let alone UFO, the effects the shows demonstrated were way ahead of their time, especially considering they were often made on a low budget and for television.
One other factor I must agree on is the standard of re-mastering. All 26 episodes in both box sets are stunning both on the visuals and the audio and are a real credit to the team at Carlton Visual Entertainment.
To finish with, I highly recommend this set. Its great television on most fronts and is a worthy rival to some of the best of Star Trek.