Answer :

This is my opinion lacking research

It actually involves the size of the island and the location. 

If it were a small island you might lack critical things you need for survival. ( con )

But you get to enjoy the beautiful scenery of the island and get to experience what its like to live on an island ( PRO ) 

Dangerous animals could inhabit the island putting your life in danger ( CON ) 

When living on the island you wont have to inhale the mostly polluted air found in cities but this more different if you're in Hawaii  ( PRO )

- last one - Some islands have volcanos and constant earthquakes which could also put your life in danger ( CONS )

hope this helped  :)