I've been a Tekken fan since I was a kid. I didn't own a Tekken game until I had a Gameboy Advance, but I played Tekken 4 at a friend's house more times than I can count, and I also got to play a bit of Tekken 3 on the side. Both games were good enough to make a lifelong Tekken fan out of me.
I remember when Tekken 5 first came out - my friend had bought a copy of it, and we played it for weeks and weeks. You could customize your characters somewhat, which was pretty new for the time, the final boss was insanely
hard, the Arcade Mode got a huge overhaul - I remember disowning Tekken 4, because Tekken 5 just trumped it in so many ways.
I've been playing Tekken 5 again recently, and I can honestly say that it holds up today just as much as it did in 2005. It isn't just as good as I remember - it's better.
Graphically, it's still beautiful. Namco knew how to push the PS2
to the limit - it's one of the best looking games of 2005, or even the PS2
's entire life cycle. Clothes, hair and accessories all move and sway with your character's movement. The characters are smooth to the point of shininess sometimes, but they all still look great. Character designs are also really good, with an amazing level of detail given to most characters on the roster, with 2-3 costumes per fighter - with other purchasable costumes for some.
Gameplay is varied and great - every character feels unique. With 33 different characters to choose from, you'll find a comfortable niche in one of them. And they all have their own story modes and their own endings. Not to forget Arcade Mode, with its rank-based difficulty system, which adds a wealth of replayability to the game. And they packaged the first 3 Tekken games on the disc as well - they're only the basic Arcade games, but that's still 4 games on 1 disc.
However, the story is a bit incomplete without knowledge of the previous game's canon ending. You can get by with just the badass opening movie, but if you want to know why Heihachi and Kazuya are getting curbstomped by JACK units then you'll need to play Tekken 4.
I recommend this game wholeheartedly, even today. I bought a used copy for $6 recently, so I know it's cheap. It's very replayable, and the quality holds up - it's a great buy.