Samsung galaxy S3 GT-I9300 4.3 Jelly Bean to 5.0-lollipop

I would like to know if it is possible to update my Samsung Galaxy S3, which is in 4.3 Jelly Bean, to 5.0-lollipop. And in this case, I would like to know :

• If it is a good idea ;


• Will my phone support it ;


• What benefits it might bring me if it is possible.

I also would like to know the best way to proceed, to update my phone.

Thank you in advance.

Edit : I have a friend that has the same phone, and his phone updated itself. Why not mine?