Karl Pilkington is certainly amusing, as the plain-speaking Mancunian alone in exotic tourist spots, but Ricky's interventions seriously backfire for me. The more he stresses his pleasure at Karl's discomfort, the weaker Karl's response becomes. You keep waiting for Karl to say, "Fuck off Gervais" and just go home, which is what would realistically happen in the situation, as it's supposed to appear. So the set-up creaks a little for all those calls on a mobile (that can always find a connection!). And sometimes Karl's asides assume uncomfortable Gervais-like cadences, leaving the suspicion of a little too much scripting or rehearsal.
Still, it would be great if Karl got to 'guest' with Bear Grylls on Man Versus Wild sometime!