I have become convinced that good camera control must be the hardest part of a 3-D game, because you see great games like Psychonauts where the camera is utterly horrible at critical moments. The camera usually follows Razputin, more or less facing where he is facing in a standard third-person view. Then sometimes, particularly for boss fights, the camera becomes relatively fixed and your movement keys are now relative to the camera’s facing rather than Razputin’s. Mix that up with sometimes having a fixed camera but your movement keys are still relative to the way your character is facing.
Handling around edges is always rough. Do you make a rock transparent, squish the camera between the character and the wall, swing it off somewhere…? Psychonauts mostly makes the camera stop at the wall while you keep moving or sometimes swings it off. There is also the problem of having objects interpose themselves between the camera and your character. The camera can be lost in the trees while you jump blindly. There is a mid-game boss fight in which the camera tends to get caught behind rocks while you are dodging around them, as if there were a physical camera on the edge of the map trying to keep you in view. Come to think of it, that would be a really great mechanic for a level in Psychonauts 2, really having a camera rolling or flying about.
The worst part is when the camera moves on its own. This is presumably to be helpful in difficult situations, but the effect is to make them more difficult. When your movement is relative to the camera, if the camera swings around 180 degrees while you are jumping, your button has just reversed your direction and sent you plummeting to your doom. The hardest parts of the game are mostly so because a change in camera angle made you lose where you were or made your keys send you in a different direction, or perhaps you could not see anything at all at that angle.
Contrarily, there are some really great moments in camera work. On a couple of boss fights, half the time is spent looking out the boss’s eyes. This works much better the second time, when the level design is less complex and therefore the camera itself is not an enemy in the fight.