A One of a Kind Experience
Note: This review mainly covers the Japanese release of the game, as it is the one I consider superior, and have played the most.
Shenmue started life as a Virtua Fighter based RPG, originally developed for the SEGA Saturn. It was the brainchild of Yuu Suzuki, head of the AM2 development studio. Shenmue is effectively his magnum opus, with an enormous amount of time and money going into it. With a price tag of $70 million, it ranks as one of the most expensive games of all time.
Gameplay: In terms of gameplay, Shenmue has been compared to both the GTA games and SEGA's own Ryu ga Gotoku (Yakuza) series. However, the focus is less on action and more on story, similar to old style adventure games. Most of the focus is on dialogue and investigation. The action sections of the games are split into two types: QTEs and FREE battles. QTEs (Quick Timer Events) are interactive cutscenes that have the player pressing a button that appears on screen within a time limit, effecting the outcome of the scene. While these have received a fair amount of criticism in other games, they have been implemented fairly well here, and work nicely. FREE battles are basically a stripped down version of the Virtua Fighter system, and pit you against one or more opponents (with one battle having 70). If you like the technical, combo based system used in the Virtua Fighter games, then you'll probably enjoy the fighting in Shenmue.
Graphics: Shenmue's graphics, quite frankly, are amazing. Detailed models and high res textures (for their time) really bring the world to life. These graphics blow away most early PS2 and Xbox games.
Sound: The music is superb, and really fits the atmosphere well. The voice acting in the Japanese version is spot on, but the English dub in the US and PAL versions is mediocre. The effects are generally good.
Overall: Shenmue is really a one of a kind game. While its slower, more methodical pace may not be appealing to all, its certainly worth getting.