にとって

From the viewpoint of
Person/Group Noun + にとって

にとって expresses “from the viewpoint of”. It is used almost exclusively with people or groups of people.
Typically, it is used to express the importance of something(or lack thereof), or values. 
It has a nuance of “as understood by“. 
If the とる (take) bothers you, you may think of it as “(as) taken in by X” — Weblio

Examples

• 彼にとって大事なことだ
  It’s something very important to him
  
  
• この会社にとって大切なお客様
  A very important customer for this business. 
  
  
• 彼女にとってはどうでもいい話だった
  The story was of no importance to her. 
  
  

にとっては

にとっては is a common variation of this pattern, used to place extra emphasis on the entity being talked about. 
This is the comparison usage of は, and essentially adds the nuance of “for X (not anyone else)”. This may imply it is not important, etc. to others. 

Examples

• 僕にとっては彼女はだれよりも大切だ
  To me, she is more important than anyone. 
  
  
• 先生にとっては、頑張らない子供は何より残念なことだ.
  For teachers, kids that don’t try are the most unfortunate thing. 
  
  

にとっては may also be an explicit comparison:

• 彼女にとってはどうでもよかったが、僕にとっては大切なものだった 
  It wasn’t important to her, but was very important to me. 
  
  
• ユーカリはコアラにとっては食料だが、他の動物にとっては毒だ
  Eucalyptus is food to koalas, but poison for other animals. 
  *Koalas see it as food, other animals see it as poison.