First of all martial arts flicks will always be redundant to some extent since there are only so many ways to pick a fight, but stories do vary as does the quality of action. Tom Yum Goong is very similar to Ong Bak in its simplistic story and the noble feeling that surrounds Tony Jaa's character. Mind you in this movie Tony is much more violent and brutal to his enemies. His sorrow at the loss of the elephants is a big part of his rage and the simplicity of the story left lots of space for action. Perhaps left simple for international appeal or for the simple fact that a simple, pure story would be more poignant. Anyway, if you go to a martial arts flick looking to pick it apart and analyze the acting skills then your a fool and should never leave your American Hollywood watering hole.
As to comparing Tony Jaa to Jackie Chan or Jet Li, are you insane?! Both Jackie and Jet are in their forties. Both are from China and went through actual training schools and academy's as well competitions. Wu Shu, Crane, Drunken Boxing etc... These are the styles these men made famous. Jackie built his comedic style from the ground up with his amazing acrobatic abilities, fighting skill and on screen charm. Now I'm not a Jackie Chan fan by any means, but credit where it is due. Jet Li was one of the youngest Chinese National Tournament winners ever and blew people away with his Tai Chi and Shaolin style Kung Fu.
How does this relate to Tony Jaa? It doesn't at all and thats the point. Tony was very poor growing up in Thailand idolizing Bruce lee in the movies. He earned every break he has in his own way, and built his style accordingly. This movie is so amazing because it not just Kung Fu and Karate for the thousandth time. Tony is a master of Muay Thai Kickboxing, which he uses 80% of the movie. Now you don't even need to know anything about fighting to notice the difference between karate (or other styles) and Muay Thai. Through the diversity of his fighting style as he battles people who using everything from crane style Kung Fu to Capoeira, you understand why comparing him to others is unfair. While he has trained in similar martial arts its obvious that he is unique. He is in the best shape of his life and just now coming into his prime. His screen presence, skill and experience mean he could be as big or bigger than Jackie or Jet in the next ten years. At the very least he is going to be a major Thai action star for years.
Also people keep in mind this is a Thai movie. Hollywood wouldn't even have finished the credits before they ran out of money if they worked with the same budget. More International success will give Tony Jaa access to a bigger budget, more talent (ie writers, language instructors, studios etc..) and allow him to grow. Its easy to bash but look at the low budget flicks Jackie Chan or any other martial artist made when they where twenty and you'll see that this movie is much much better than most.
Remember it all just opinion people, everyones got one. PacManPolarBear