It has its faults, but if you're a Tekken fan, there's no way you're coming away disappointed. Sadly, the game's online is probably the weakest part, with very hit or miss net-code leading to lag. Sometimes it's fine, other times it's less so. It's always playable, just not ideal. Namco realise that and want you to know they're working on fixing it up, "To improve the online game experience for players ... Namco Bandai games is developing a downloadable update which will be available as soon as it has passed rigorous testing procedures."
Sadly, there's no real date on the patch. We hope Namco get it out before their playerbase move on because, honestly, we intend to play plenty of Tekken 6 over the coming year.