Giving it an 8/10 like last week.
I just felt that the underlying purpose of the journey was a bit flimsy, and they didn't compensate by any entertaining distractions* along the way, for example with Vietnam's driving school or Botswana's rallying (and limping home afterwards). The scenery was fantastic and there were some good bits, Jeremy's handbrake solution and the river crossing being highlights, but nothing from the special really gripped me.
As an example, when Richard's Subaru broke down there was nowhere near the emotional connection or genuine tension as there was when Oliver sank in Botswana. It just sort of happened, and he sort of arrived the next day. Woo hoo.
Also, I agree with those here that think the 120 minutes running time was a bit too long. But saying that, I don't know if they could cut down to 75 whilst keeping the flow. The whole episode felt slower, there weren't as many obvious pieces of action to cut (e.g. Vietnamese Stig). To be honest though, I'm the sort of person that would rather see a more full 120 minute version aired rather than seeing bits cut, even if bits feel slower as a result.
Still, really glad I don't have to wait 10 months for the next episode. I've quite enjoyed this one. Yes, even the P45.
* not to excuse cheap scripted failures (I'm looking at you, India)