Tekken 5 does exactly what it's predecesors have all done. It's just an extremely good fighting game.
At its core, every Tekken game is basically the same. They all play out the same. They all take place in the King of Iron Fist Tournament, where fighters from around the world come together to see who's the best. Classic characters like King, Yoshimitsu, Kazuya, Paul and Law are back, and if you knew how to use them before, you shouldn't have any trouble now, since their moves are all basically the same, with some new tweaks. There are some new interesting characters, like Asuka Kazama and Raven. The new characters have some awesome fighting styles and are a lot of fun to use.
While the gameplay is without a doubt, very similar to the last installment (with the exception of the push/pull grapple technique), there really isn't anything that needed changing. To prove that, Namco added an Arcade History section, where you can check out and play the first three arcade versions of Tekken just like they were in the arcade. What really takes the cake in Tekken 5, are the amazing visual effects. The character designs, battle areas and even game menus are just absolutely gorgeous. The soundtrack is also a very nice touch, and it all meshes together perfectly to amp up the already awesome game experience.
There are two important modes of play in this game, which are, Story Mode and Arcade Mode. In Story Mode, you choose a character, discover that character's reason for being in the tournament and fight through nine stages, where you are then rewarded with an ending and a new character unlocked. Arcade Mode is where you choose a character and fight against AI opponents with the objective of raising your rank. You start off at Beginner and go on to Kyu, Dan… all the way to Tekken Lord. After each battle, you obtain Gold that you can spend in the Customize Mode, where you can buy new outfits, hairstyles, accessories and "alternative costumes" (like the costume for Christie which is actually Eddy Gordo!).
Those are really the only big modes in the game, aside from your standard Time Attack and Survival Mode. One thing that deserves to be mentioned in my opinion, is the Devil Within game, a kind of beat-em-up game following Jin Kazama, as he tries to uncover the secret of his Devil Gene curse. It's not very innovative or out of this world, but it is a step up from past versions like Tekken 4's "Tekken Force", and actually pretty fun. It's worth a play through, since you are rewarded a lot of gold for playing, and can find more than one big surprise from playing it. There's just this wonderful feeling I get from playing Tekken 5. This feeling that after 16 years, the game formula never had to radically change to make itself bigger and better, and that makes it golden in my book.