The 26-year-old - who cost Arsenal £35million - has hit the ground running in his debut Premier League season.
The Chilean forward is the Gunners' leading goalscorer this term with 22 to his name already, but insists the praise must go to his new team-mates.
And the former Udinese man is expecting 'many titles' at the Emirates.
"When I arrived at the club I didn't know the players that well, but I was really surprised by everyone's quality," the Chilean said.
"I am not saying this just because it's my obligation to do it as a club player. Every Arsenal footballer has amazing quality.
"Being part of a team like this makes me very proud. I am willing to win many titles here."