The thing that makes Resident Evil 4 such a good game is the emphasis on action. And it never wears off after you start.
Resident Evil 4, like previously mentioned, is very different from its predecesors. The camera is the main change. No longer are you stuck with a fixed camera view, but the action is now viewed from over the shoulder, zooming in when aiming. Aiming, too, has been changed. Instead of auto locking like previous games, is now done with a laser system. Once you ready a weapon, a laser will emitt from it, making aiming very easy, even though, for the sake of realism, Leon won't hold his weapon very steady.
The weapon system has also heavily changed. Instead of limited item slots you now have a case in which you can organise weapons at your own will. You can also buy weapons at a merchant, a well designed system. Also, you won't have to be as spary with your ammo as previous games, though you shouldn't always run around gunning like a loonatic. The combat in Resident Evil 4 also is one of it's highlights. It's always tense and exciting, and you'll definitly enjoy shooting someone's head off again and again.
Resident Evil 4 also looks down right incredible, perhaps even better then the average Xbox game. The character models and facial expressions look very believable, and it makes you think you're watching a really freaky horror movie. The enviroments themselves are just as good as the characters. Water looks beatifull, trees look beautifull, everything looks beatifull and it's just incredibly satisfying to look at the games world.
Survival horror needs thrilling sounds, and RE4 delivers that in spades. When fighting a regenerator, you'll hear him gasping sending a chill down your spine making you want to kill them. The guns themselves also sound very realistic it's just marvelous to hear the TMP shooting the heck out of El Gigante. The background music also fits the situation. When fighting in the village for example, the background music just sounds creepy, making you think there's a chainsaw freak nearby. The voice acting is also pretty good, but it often sounds pretty faked, not quite as good as it should've been. But this is to be forgotten if you know how good the rest of the audio is in Resident Evil 4.
Resident evil 4 is also a pretty long game, you'll need plenty of time to finish it, as expected by the two discs. About 10 to 20 hours will be needed to finish it, and even after that you'll want to play through the game over and over again just to reexperience all the horrors. It is that good. After finishing the main game, you'll unlock all kinds of bonus extras, like Mercenaries and Asignment Ada. This all adds up to the incredible lasting value, even without some kind of Multiplayer.
All in all, RE4 is a must have for gamecube owners. Be alert though this is not a game for the sesitive of gamers. Lots of blood and gore will splatter around and that doesn't even get close to how scary the game can sometimes be (though it isn't close to the previous titles). But if you aren't, check this game out. Renting does this game no justice. Buy it, enjoy it, live the nightmare and experience what a great experience Resident Evil 4 is.