Like Shaun and DT1 I quite like his shows. You've got to remember that he's an actor and therefore says "knobby things in a knobby manner", I think they pay good money to be trained to do it as well as he does. Either way you have to admire his swimming achievements on that show, they certainly took guts, determination and sheer mental and physical strength.
To be perfectly honest, if someone offered me 6 months of extreme fishing around the world in exchange for me acting like a knob, I'd bite their hand off.