If you intend to spend the rest of your career working for BA then being bonded to them for seven years isn't a negative point - it simply doesn't make a difference.
Not that cadets have a huge choice in today's industry, but I still believe most UK-based cadets would rather fly for BA than any other airline. And I do think other airlines should take BA's example with their recruitment programmes and shoulder some of the financial burden - even if it doesn't seem pragmatic from a purely business perspective. But as to not deviate far off topic I won't delve deeper into it than that.
On the whole I thought "A Very British Airline" was quite good - and certainly interesting. Clearly some of it has been dramatised for television purposes - particularly the cabin crew recruitment where I believe things were made to appear tougher than they actually were (only two failed after all).