I watched 19x06 yesterday, and I found it to be okay. I understand the enthusiasm a lot of FGers feel when one of the specials is on, and I agree that the scenery was nothing but stunning. Yet, I do not see this on one level with earlier specials. It was certainly not as ridiculous as India, it rather had a serious tone to it like earlier specials, which I like. The problem I have was that the happenings in special seemed kind of pointless to me.
Of course, you can question the point of any of the specials since none of them had a serious purpose. And still, they always managed to give it a whiff of the three blokes actually doing something and actually trying to succeed. Now, with Hammond turning up in the only decent car here and May coming with a nice, yet useless car for the expected conditions, fail was pre-programmed. I wouldn't expect James to come in a Bowler Wildcat, and he has often made questionable choices (such as the Aston Martin N24), but choosing an 850R over any "normal" Volvo Estate for a trip through Africa does not really fit Captain Slow, does it?
Also, going on a search for the source of the Nile, given that it is actually unknown, seemed to be a dodgy plan to begin with. If scientists and researchers have not found it yet there is no chance they will, even if they will it must be proven with scientific standards, and the only reason they did this anyway is having a (arguably lame) cause for driving through Africa. There must be better ways to fabricate a reason for such a special, otherwise they can as well just say they get random cars and drive around being funny. Same with the "reason" they had to sleep in their cars - the hotel was a clear set-up to get the right arguments for going where they went.
That said, I did not dislike this special as such, I had a pretty good time watching it. I had one genuine laugh when I realized that James had taken his new engine protection thingy from Jeremy's passenger door, that was great. Same thing when they took the shit out of Richard for his poor television show, you could see his laugh was genuine.
Overall, I would give this a 7/10. A mixture of very beautiful scenery and avoiding to clown around stand against the somewhat slow and pointless-seeming challenge as such.