I've just finished watching the first season this week (yes, I have copies of the episodes!) and it really stands up well against the other more well-known 70's BBC drama series. I'm missing a few episodes of season 2 which I'd like to get hold of but I'm hoping that someday this will get released on DVD. Especially with the movie Flyboys coming out later this year.
I'm aware that most of the flying scenes were done with radio controlled models but it really doesn't show that much. The switch between models and actors in static full size replicas is done very well and the acting of all the main cast is of the quality you'd expect for this ear of the BBC.