Can't help but feel that there is more potential for Tekken 6.
You have 40 brawlers who each can perform over 80 different moves. Yes at least 80 different moves, and that is with using only 4 buttons (each correspond to a limb of the fighter). Now, purists will love the depth and complexities of the game but it can alienate all but the most hardcore gamer who intend to spend time learning the intricacies of the game. The rest of us may just learn a few things and button mash our way through.
Despite that, the fighting is superbly polished and balanced though once you're caught in a combo, it's almost impossible to get out of it. The characters themselves have their own story and some are pretty humourous in nature. Since it's my first Tekken, it's interesting to learn how a panda / grizzly bear, kangaroo or training dummy be part of the roster when you play them in the Arena in Scenario mode.
Yes, besides the usual 1 on 1 fights, there is a Scenario mode using the Tekken engine. Spanning over 30 chapters / stages (each quite short actually), you battle your way with a character and a AI-aided partner following the Tekken story. It is an admirable effort to combine the fighting modes into a action game like Final Fight, but however it gets after a while. Luckily each stages are short, and the stories are interesting enough to make you have one more go at it.
Lastly, the multiplayer while robust, is still not as good as the Street Fighter series which is pretty much the standard right now. Having say that, it's easy to go online and have a battle or 2 though only the hardcore gamers would stick to it longer than after a few fights. Suffice to say, it has yet to replicate the arcades where gamers would willing shed quarters to fight each other for hours.
Overall, I would still recommend Tekken 6 to be part of your gaming collection or experience, if only just to get its trophies or achievements.