I rather like Vettel. I intensely dislike his finger but I rather like him as a driver, as a competitor and as a scholar of F1. Sure, he has his moaning moments but then so do all drivers.
I believe he's been quoted as saying that most F1 greats have driven for Ferrari. Given his quite simply explosive rise in the sport, if he's truly focussed on writing his place in F1 history as one of the true greats, he will need to accomplish a good deal more. Moving to a prestige team, such as Ferrari, and winning there will be a further step towards that goal, and a silencer of those critics who will otherwise always be there to say that it was the car rather than the driver.
For me, Vettel has the capability to be a modern day complete F1 driver. He can take understanding of the technology to a different level. I'm talking about not just managing tyres and race strategy that goes way outside the race, but to someone that can view the whole Championship as the journey rather than race by race. I'm a JB fan, btw, but I really do admire what Vettel's achieved. He's undoubtedly had the faster car on many occasions in the past three years. When he does he's absolutely clinical at closing out the win or the points - far superior to anyone else. When he doesn't, yes - he moans like any other driver, but he's maturing and now brings home more points than before. That's more than great driving on the track, it is incredible organisational awareness, the ability to detach thinking from his immediate situation.
He's clearly supported by a great team at RBR - the question would be whether he can bring sufficient learning to a new team and galvanise them. Do that, especially without Newey, and I'll take my hat off to him.