This is a damn impressive game. It's based on a fantasy novel by a Polish author who's name escapes me but it's a really cool concept.
The world is very dark. It has a strong Eastern European flavor (as might be expected) but it's still pretty familiar. Your PC is a Witcher. A sort of fighter/mage combo who relies on alchemical potions to boost his abilities. The alchemy system is interesting though I've noticed I often end up carting around dozens of different regents without using them
There's only a half dozen spells in the game but they're all designed to complement the primary job of beating on things with your swords. Fairly vanilla stuff, gusts of air, cones of fire, a shield ect. but they're easy to use in the middle of a frantic flight so that helps.
Combat is not unlike Diablo where you click on enemies until they stop moving but to make an interesting twist you need to chain moves into combos by clicking at the right time. Click too soon and you mistime an attack and leave yourself vulnurable. there are also 3 different combat styles. One for big tough enemies, one for agile enemies and one that does heaps of damage to mooks surrounding you.
You are limited to 4 weapons (though I've only ever used two) You have a heavy weapon like a club or axe, a light weapon like a dagger and two swords, one steel, one silver. The steel sword is used against human enemies while the silver sword is better used for fighting most monsters.
A rather odd aspect of the game (and what gets it it's 18+ rating) is the amount of sleeping around you can do. I'm only in the second chapter and my character has probably picked up half a dozen women. It does a fade to black scene then you get a card showing your 'conquest'. Nothing too racy so far. Basically just medieval pinup girls . In the European version the cards show boobs. If it's not your cup of tea you can also avoid this bit completely. Gerald is a pretty obvious flirt so it's easy to take the puritan route. I think it suits Geralt's personality though.
All things told I'm quite enjoying The Witcher. I've probably put in 40 hours to get 3/4 of the way through Chapter II (accomplishing sidequests) and there's 5 chapters total (plus downloadable adventures I haven't gotten to yet) so I can see it keeping me busy for quite a while.