If you have yet to play this, then slap yourself in the face :P
+A.I., aka no zombies:
no longer are you facing dead brain matter enemies from past games. The ganados provide much more of a challenge in RE4. Not only do they attack in groups, but use various of tools, and will surround you intentionally to insure your death from all sides. Unlike zombies, if you steady your aim for too long, a ganado will occasionally sidestep to throw your accuracy off.
+Camera perspective:
the new and innovative perspective of "over-the-shoulder" angle brings the action and intensity much closer for a cinematic feel (even more so if played in wide-screen), which work intuitively with the controls. No longer is the series plagued with the obscure and fixed camera angles, where enemies remain off screen and unseen.
+Boss fights:
bosses have always been grotesque and delightfully unique monstrosities, though RE4 continues this trend, but ups the ante in entertainment. In past REs, most patterns for boss fights were slowly limber away, pull off a few shots, move to a new corner of the area, a few more shots, and then repeat. However, in RE4, due to the new perspective, boss fights become more modern to the average action game; ie: aiming for specific weak points or using the environment to your advantage.
+Merchant and upgrading:
there is also some RPG elements too in RE4. By visiting a friendly (why?) ganado in every new area, you can purchase a variety of weapons and upgrades. Each weapon has it's own and unique stats, and through each upgrade, can improve it's reloading speed, ammo capacity, power, and accuracy.
+Specific hit points:
tired of shooting zombies in the general body area for a kill - well - in RE4 you can aim for a more precise shot. Depending where you shoot, determines how effective the kill can be. Head shots will respectively bring an enemy down quicker then a full chest one - aim for the leg will drop him down to the ground temporarily - going for the arm can make the ganado drop a weapon, if it has one.
+Interactive cinemas:
just like that of Indigo Prophecy, the cut scenes will require attention for a sudden button mashing or press. This requires players to stay on their feet and keeps the action going, regardless of the cliche "cinema break." Which should please those familiar with the Metal Gear Soild series.
MISSES:
-No puzzles:
even though it's refreshing that RE4 eliminates the unecessary backtracking for key items to progress forward. The puzzles in RE4 are just juvenile. If anything, RE4 puzzles can be more like those in Silent Hill.
-No thrills:
of course RE4 has it's shares of horror, but lacks the quick and sudden surprises that past RE titles have had. This could be because of the new perspective which allows you to see all enemies at all times. Most that have played believe it has become more of an action game then that of survival horror.
- Got ammo?:
even though a player can purchase weapons and upgrades from the merchant, he doesn't sell ammunition. Which requires random crate and box smashing for ammo.