The first is with regard to Paul Foster's girlfriend. I think I can see what they were trying to do with the story here, but I agree with you guys that it doesn't work. As Eugene said, she needs to be established a couple of episodes back; this is the kind of story arc that reaps rewards only if you sow it early. To me, an exemplar of this is the way in which Matthew Macfadyen's character reacts when his girlfriend, played by Natasha Little, calls him after the incredibly intense events of episode 5, series 2 of Spooks (I believe they call it MI5 when they show it to you guys). There's a huge amount of drama in the secrecy and high stakes of a role like that held by Foster, if you can make it seem credible; unfortunately in UFO it is scarcely that, and what do they do with it anyway? They waste it. It's worth watching a little of that second series of Spooks to see how they build up the impact in having an incredibly fraught, clandestine career and then trying to socialise normally.

The second is with respect to having to kill the alien. I agree with Ben here, this whole thing is wasted. Both of you seem to agree the alien needs to die - I wasn't so sure about this, I thought it would have been fascinating to have had some kind of communication and to have seen where this might have taken the series. But even if the alien had to die, the whole episode was building up to this. The implications if the alien had lived are so crucial, personally to Foster but also to Straker and Shado as an organisation, that to just gloss over it was deeply, deeply unsatisfying. Once again, the drama seemed to be hidebound by the 50 minute format leading to anything really interesting being glossed over in favour of wrapping it up neatly so we can start afresh next week.

Disappointing.

While I don't like some of the changes - end of year cliffhangers most of all - some of them have demonstrated a better utilization of the medium.

With that said, I don't think we can criticize a 1969 TV show because its stories were self-contained inside a 50-minute format.  Virtually all shows conformed to that paradigm.  At the time we really only had the self-contained story, the mini-series or short form, usually an adaptation of a novel and the never-ending soap opera format.

Taken by the standard of the norm at the time...  it still doesn't quite work because we don't get Paul's actual emotional attachment to the girl, but let's not judge by 21st century televisions standards, either.