Resident Evil 4 is an amazing Action / Adventure game.
There isn't much I can say that hasn't been said already, so I'll make this short. Resident Evil 4 is one of the best Gamecube games to be released, and one of the best games to ever be made. This is the pinnacle of the Resident Evil series and I would love to see Capcom top this.
There's a ton of differences between the classic Resident Evil games and 4, as the controls and camera angles have been completely revamped. There's no more pre-rendered backgrounds or tank control movements. The 3rd Person shooter perspective gives Leon more and faster movement to keep the game at a faster pace. So it's hard to compare this game to the classic RE titles, but they share enough qualities. While I loved the early RE titles as much as anyone, RE4 clearly tops them.
----------Battle System----------
Resident Evil 4 is a 3rd Person, Over the Shoulder view, Action / Adventure game. This is so far the most action packed Resident Evil game I've played, atleast out of the main six titles. Resident Evil 4 kinda drops the survival element of the previous games, you have unlimited saves, you can buy weapons and health, and you find more ammo through out the game than the previous ones.
There isn't much puzzle solving in the game, that was my biggest disappointment, but it wasn't a huge loss as there was still a few interesting puzzles. Resident Evil 4 also requires you to babysit Ashley in some missions, but you can use her as a tool in some cases, similar to the extra characters in Windwaker or Beyond Good and Evil. The babysitting missions aren't tough and you rarely have to watch over her, but you can tell her what to do like; wait, follow or jump into that dumpster. So you can keep her out of danger is a flood of enemies start to roll in. Ashley has her own health meter, and if she dies or gets kidnaped then gameover.
Even though this is the easiest Resident Evil I've played, I still died more often in this than the previous ones combined. There is a ton of moments in the game that will kill you by suprise, but starting over is pretty simple and they usually leave you at the last door you came in.
There's moments in the game will a required button combination will pop up, even during cutscenes, and if you don't tap the right buttons fast enough then Leon will die. So you can't even relax during cutscenes.
----------Characters / Story----------
You play as Leon (from Resident Evil 2), who is sent on a mission to save Ashley the kidnapped daughter of the President of the United States. As Leon is investigating around the area of Spain, he encounters a hostel village and all hell breaks loose. Leon eventually saves Ashley, but by then they're both poisoned by the Plauga virus, and they're behind enemy lines and need to escape a giant castle to survive.
The story is a bit cheesy, but still very fun with a ton of surprises and interesting characters throughout the entire game. There's moments where Leon will talk through his walkie-talkies type thing, which is very similar to Metal Gear Solid, these scenes are especially cheesy with stupid one-liners.
----------Graphics----------
Wow.. I just can't think of any other game that surpasses Resident Evil 4 in the graphics department this gen. The character models are so freakishly humanlike it's scary. The gore is fantastic and extremely creative. The level designs are huge, complex and highly detailed. There's a ton of enemies, huge bosses, a large assortment of weapons, items, and so on. The cutscenes are all in-game made. The game is fully 3D and don't use the pre-rendered backgrounds like the previous Resident Evil's and still manages to look better than those. I can't think of any blemish or flaw in the graphics.
----------Sound----------
The voice work is great and over the top (not in the original Resident Evil sense). The music is minimal but effective. The sound effects are great. There's really nothing bad about the sound either.
----------World Map----------
The world map is a typical 3rd Person Adventure style map, where you linearly go from room to room. The game is separated in chapters. Each chapter has it's own sub-map that tells you which rooms you've been in and what goals you need to accomplish. The sub-map will tell you what room to go to, where items are, save points and merchants. Some chapters end with a boss battles or mini-boss battles. You can save at any typewriter in the game without the use of ribbons, so save as many times as you want.
----------Time to Complete Game----------
Final Stats
Hit Ratio: 76%
Enemies Killed: 970
Number of Times Killed: 87
Clear Time: 20:01:05
Number of Saves: 105
I played it on Normal. After you beat the game you unlock two new weapons, and two new mini-games.