I find Monbiot a very frustrating pundit. I generally agree with him but he almost invariably fails to get his arguments across effectively. Rather than keeping emphasis on a salient point which has a chance of cutting through, he launches into mini-speeches where his key argument is lost in flowery language or diluted by digressions, and which are subsequently easily ignored or deflected.
I wouldn't mind so much but as he's one of the few left-wing commentators who gets a degree of unchallenged airtime it always feels like a missed opportunity. Although, I suppose if he was more forensic and more effective as a proponent of 'the left' he probably wouldn't get the platform he does.