How does he compare to the other greats?
Well, he's a better in ring worker than Austin, Hogan and The Rock, if you disagree with that then you're not looking at this objectively. How many 5* matches have those guys had really? Hogan: none, Austin: possibly 3 at a stretch? & The Rock: probably 4 and Cena at WM28 was one of them. Cena has had countless classics, why? Because he is a man for the big event and knows that if he doesn't deliver, the PPV fails.
Hogan brought wrestling into the mainstream, while Austin changed the perception of pro wrestling to make it cool but Cena has done the hardest thing of them all, overcome the negative stereotype of pro wrestling today & taken it global. No other top guy in history has maintained the work rate that Cena has. With 15 years on the road, 11 years as THE man, Cena has done close to 200 house shows a year for over a decade. His run at the top certainly rivals Hogan's in the 80s.