The Truth has been one of the most consistent scorer out there. I think he's one of the few players (along with Kobe, Lebron, AI, Arenas, and Wade) that when he gets going, theres absolutely nobody that can slow him down, but the difference is hes been doing that longer than any of the examples above (except for AI and maybe Kobe).
He's got the whole package! Hes got such body control when taking to the hoop, he doesnt make it pretty like Lebron, but hes extremely effective and is able to draw fouls. He can also shoot the outside shots and post up if needed, and one of the plays we havent seen that much during the playoffs is the Walker lob pass to Pierce under the hoop. He's also a good rebounder and good assist. This season he has impressed everyone with his lock down D.
With all of that said, he still hasnt received enough TV coverage to be considered a hall of famer in my opinion. For example, when talking about the best players in the league, few would place Michael Redd in that department even though the man has been a great shooter and one of the best scorers for the last 5 years.
However, with Pierce's consistency and no signs of slowing down, I see Pierce putting up great numbers for at least 3 more years. I think that'll be enough to place him in the Hall of Fame. Besides, I think we already know that Pierce is amongst one of the best Celtics ever, and thats all that matters.