#2 In most cases the problem with the camera view is that it effects the way the player preseves the movement buttons to work. If a character was facing towards the player would they push the right button to go right or the left button from the characters perspective? Camera views that switch causes the player to get disoriented but do open the view to reveal ones surroundings or focus them on a given location.
Problems with cameras is that the Character gets in the way. A character may get in a place were the camera is not looking and you have to bang against the walls until you get into view. Things you want to see are obstructed from view.
I hope that helps.
Just a note on perspectives for those who wonder:
1st person is were you do not see your person except maybe arms or weopon. Like Doom or Ultima Underworld.
2nd person is were you see your person in front of you like Tomb Raiders.
3rd person is from above or at a distance.