"Honestly, I don't have to use up many words to say how good he is, the results are there for all to see.
He has won everything there is to win and has been on the same great level for so many years now, which is possibly hardest of all for a goalkeeper.
Spain almost never concede goals and Casillas is the main reason for that."

— Juventus and Italy goalkeeper Gianluigi Buffon on Casillas prior to the UEFA Euro 2012 Final.

Widely considered by pundits, as well as both former and current goalkeeping colleagues, as one of the greatest goalkeepers of all time, Casillas was given the nickname "San Iker" ("Saint Iker") throughout his career, for his precocious performances as a youngster, and due to his ability to produce acrobatic and decisive saves.
In his prime, he was a spectacular, well-rounded, and athletic keeper, who was known in particular for his outstanding agility, reflexes, consistency and shot-stopping, as well as his foot-work, positioning between the posts, concentration, and speed when rushing off his line in one on one situations; he has also stood out for his penalty-saving abilities.
In spite of his reserved character, he has been highly regarded for his strong personality, calm composure under pressure, ability to organise his defence, and leadership from the back throughout his career, as well as his reading of the game.
Gianluigi Buffon described Casillas as the best goalkeeper of his era with his hands.
He was also known for his ability to save the ball with his feet, with former goalkeeper Manuel Almunia likening him to compatriot Luis Arconada, who also served as an inspiration to Casillas, and to whom he was often compared throughout his career, due to his quick reactions, movement, and excellent footwork.
Regarding Casillas's playing style and goalkeeping ability, Almunia commented in 2017: "Iker's a strong goalkeeper, leaps well, good diving in either direction... between the posts he moves like a cat."

A precocious talent in his youth, Casillas has drawn praise for his longevity and consistency at the top level, as well as his discipline in training; despite his reputation and goalkeeping ability, however, due to his lack of notable height and strong physical attributes, he has been criticised at times by pundits for struggling to command his area, in particular against aerial threats, and for his unsteady handling and indecisiveness when coming out to claim crosses, as he often preferred to punch the ball away.
He also received criticism in the media for a series of errors and less consistent performances in his later career, as he lost some of his speed and mobility with age due to his physical decline.
Although he has occasionally been criticised by pundits for his limited skills with the ball at his feet in comparison to other Spanish goalkeepers, Casillas's distribution with both his hands and feet has generally been reliable throughout his career, and he is capable of sending the ball into deep areas of the pitch with his long throws and kicks with his left foot.
"Honestly, I don't have to use up many words to say how good he is, the results are there for all to see. He has won everything there is to win and has been on the same great level for so many years now, which is possibly hardest of all for a goalkeeper. Spain almost never concede goals and Casillas is the main reason for that."
— Juventus and Italy goalkeeper Gianluigi Buffon on Casillas prior to the UEFA Euro 2012 Final.
Widely considered by pundits, as well as both former and current goalkeeping colleagues, as one of the greatest goalkeepers of all time, Casillas was given the nickname "San Iker" ("Saint Iker") throughout his career, for his precocious performances as a youngster, and due to his ability to produce acrobatic and decisive saves. In his prime, he was a spectacular, well-rounded, and athletic keeper, who was known in particular for his outstanding agility, reflexes, consistency and shot-stopping, as well as his foot-work, positioning between the posts, concentration, and speed when rushing off his line in one on one situations; he has also stood out for his penalty-saving abilities. In spite of his reserved character, he has been highly regarded for his strong personality, calm composure under pressure, ability to organise his defence, and leadership from the back throughout his career, as well as his reading of the game. Gianluigi Buffon described Casillas as the best goalkeeper of his era with his hands. He was also known for his ability to save the ball with his feet, with former goalkeeper Manuel Almunia likening him to compatriot Luis Arconada, who also served as an inspiration to Casillas, and to whom he was often compared throughout his career, due to his quick reactions, movement, and excellent footwork. Regarding Casillas's playing style and goalkeeping ability, Almunia commented in 2017: "Iker's a strong goalkeeper, leaps well, good diving in either direction... between the posts he moves like a cat."
A precocious talent in his youth, Casillas has drawn praise for his longevity and consistency at the top level, as well as his discipline in training; despite his reputation and goalkeeping ability, however, due to his lack of notable height and strong physical attributes, he has been criticised at times by pundits for struggling to command his area, in particular against aerial threats, and for his unsteady handling and indecisiveness when coming out to claim crosses, as he often preferred to punch the ball away. He also received criticism in the media for a series of errors and less consistent performances in his later career, as he lost some of his speed and mobility with age due to his physical decline. Although he has occasionally been criticised by pundits for his limited skills with the ball at his feet in comparison to other Spanish goalkeepers, Casillas's distribution with both his hands and feet has generally been reliable throughout his career, and he is capable of sending the ball into deep areas of the pitch with his long throws and kicks with his left foot.
Iker Casillas