First off, here's a wizardly word of warning: Harry Potter and the Prisoner of Azkaban is being released on all the consoles and the PC. You'd expect all four games to be the same, but there are vast differences between the consoles' version and the PC one.
To all intents and purposes, the console version is an altogether different game. And it's a far, far superior one. If you want to spend your money in the wisest way, get Prisoner of Azkaban on PS2, Xbox or GameCube if you can.
Just as Prisoner of Azkaban the book (and possibly the film) is better than its predecessors, so is the game. For the first time you can play as Ron and Hermione as well as Harry, and this isn't (on the consoles at least) a merely cosmetic and Potterphile-pleasing endeavour.
Each of our three heroes learns different spells and has their own particular skills - Ron is especially adept at discovering secret passageways, for example, while Hermione can crawl through tight spaces. (Which is a bit odd - are Ron and Harry incapable of crawling?) You can swap between each of the characters as you please and you'll need to use their individual skills and spells to solve particular puzzles or defeat specific monsters. While in control of one character you can call on the help of the others, too, and there are a few rewarding puzzles involving placement of characters that make full use of the wizard-swapping system. Great stuff.
The game's divided into school days and as well as dealing with the story proper you'll have to attend lessons and fulfil other objectives. There are also a number of Zelda-style dungeon areas - so Zelda-style, in fact, that they nick wholesale such staples as sliding ice blocks around. They're most often used as spell-obtaining exercises and they're genuinely absorbing, even if combat with monsters is usually overlong and on the tedious side.
In fact, we were pleasantly surprised by how much fun the single-player game is - true, it's rather derivative and redolent of a hundred other third-person adventure games, but it's suffused with that Potter atmosphere and is genuinely involving. The PS2 version of the game also offers some brilliant Eyetoy minigames that have you de-gnoming the Weasleys' garden and splatting chocolate frogs, so if one version of the game really tops the bill, it's this one. If you've got an Eyetoy, of course.
With each Potter game EA get better and better at doing the subject matter proud. This isn't just a cash-in - it's a fine little game in its own right. Let's hope the inevitable Goblet of Fire is even better, eh?
Harry Potter and the Prisoner of Azkaban is out now on PS2, Xbox, Gamecube, PC and GBA