The Rock (character) really died at Summerslam 2002. He was booed in favor of Brock Lesnar. In a promo a few months prior to that match, for the first time in years he said "I" instead if "The Rock" and spoke in first person. From then until his heel turn as Hollywood Rock, his promos became less and less interesting. Hollywood Rock was okay, but it lacked in the sheer composure and "cool factor" he had prior to that. The old Rock was more methodical and calculated in his promo delivery. It really built tension between himself, the audience, the people at home, and the wrestler he was taking about (watch his promo against Billy Gunn from 1999, the one where God is involved). Following Summerslam 2002, that disappeared entirely and we were left with a more energetic and unfocused Rock who cuts extremely corny promos that occasionally seem like half baked impressions of what he used to do. He smiles, when he never used to smile. He laughs at his own jokes when usually he delivered his lines and insults with a polished and stern demeanor. This became extreme when he returned to WWE to host Wrestlemania, and continues all the way to this day.

I understand people like The Rock, I understand that he's still charismatic, that he's still very very talented. But to me, The Rock that I worshipped as a child met his death at Summerslam 2002, and his funeral was at Wrestlemania 19 against Steve Austin. Everything after that Summerslam was less and less entertaining and continued to be that way.

Edit: I'm a little harsh only Hollywood Rock, it was more entertaining then the rest of his post-August 2002 run, but from a personal standpoint it wasn't the same for me.