I'm going to hold off rating until I've seen the 720p version, because I missed the first 20 minutes or so and I watched the rest on the BBC's (rubbish) live stream.
However, from what I did see, I thought it was ruddy awesome, a good lift out of the slight mediocrity of this series so far.
They were completely and utterly totally barking fucking bonkers to drive straight up to 17,000ft though, and that dune at the end was terrifying, to say nothing of el camino de muerte.