First of all, the presentation of the game is beyond awesome. The editing, the rhythm, the angles -- EVERYTHING about the cinematic parts and the cutscenes is better than 88% of the action crap Hollywood feeds us. Kudos to the director of RE 5.
The gameplay is very well paced, action sequences are usually followed by simple puzzles and every few minutes something new and spectacular happens. The game flows naturally and it's not very likely you'll get bored or stuck in a frustrating way at any point.
The controls are quite OK once you get used to them, but in the beginning you might be slightly annoyed by the fact that there is absolutely no way to walk & attack at the same time.
The inventory management is not perfect. To refill your health could sometimes be a long surgery, requiring excellent coordination: request => combine => equip => use.
Your team mate can be controlled by either a human player over the internet or by the AI. If the latter is the case, the AI works quite well most of the time, your partner rarely gets in your way and could even be quite useful at times. Apart from that, there is constant interaction between Chris and Sheva, contributing to an overall 'live' feeling of the game -- you are not alone, someone's watching your back, sharing your emotions.
The action part is the heart and soul of this Resident Evil game and it is absolutely marvellous. There are plenty of enemy types and variations for you to gun down, all of them behaving in a very convincing manner. Even though extremely hostile, you can still feel their fear of (permanent) death as they slowly approach you, trying to lay low and dodge your laser aim.
It is important to mention that this game is not really a survival horror. It is an action game. It will not make you shit your pants and will not give you nightmares.
However, it will make you feel you are in the middle of an extremely well-made action flick.