I read this on the FP group Prehistoric Explorers Club - but it was originally posted by The Scottish Media Lab. It throws up some interesting points which I've put in italics:

"Part 2 of Brodgar was a lot of fun and generally well done. Seems some are objecting to some of the programme's comments, In short:
You could be left with the impression Ness of Brodgar started with developments on Orkney. Nope the Camster Cairns in Caithness are earlier and we have tombs/ chambers of related but less sophisticated design advancing up the West Coast over centuries beforehand.
Yeah there are standing stones elsewhere - the megalithic arrives from Europe where it likely meets already fairly advanced lithic cultures. It's the scale/ proliferation that 'advances' out of Orkney, which forms a fairly broad cultural horizon.
These developments don't take place in the context of nation states and don't involve invasions or political take overs. Instead ideas and implements are passed on or traded, then developed or forked along quite different lines. E.g. for all the connections and shared ideas we are finding between Brodgar and the Stonehenge region there are considerable regional differences - most obviously we have no sign of a massive, habitable complex like that found at Ness of Brodgar.
The suggestion in the show that the unusual and fascinating burials in the Tomb of Eagles may have in some way allocated eagle bones or talons to individuals within a collective grave . . . At present what we appear to have is an Orcadian social structure that is collectively tied to a widespread ritual landscape while developing some unfamiliar/ unconventional social hierarchies..."

The comment goes on quite a bit longer and I suppose I should really be commenting on FB but it often seems a bit pointless. The writer says, while drawing comparisons with Stonehenge, no sign of a massive habitable complex like the one at the Ness of Brodgar has been found near Stonehenge. To me it seems that although Stonehenge is comprised of sarsens and bluestones any associated structures would probably have been built in timber and may well have disappeared without trace. Stone was used on Orkney because timber wasn't available.