The former Liverpool midfielder has completed his €160m move to Barca in the last 24 hours.
"My opinion doesn't matter, but the price has gone a bit high, that's what the market dictates," Rakitic said after victory over Levante.
"Every great player is welcome here. I congratulate the president and everyone else who made it possible for him to be here.
"He is one of the family now, we are going to enjoy him a lot, he's now at the biggest club in the world."
The former Sevilla star did though make reference to the fact Coutinho can't play any part in Los Cules' Champions League campaign.
"We are happy another player has joined us, one who is among the very best," he noted.
"Obviously, he can't play in the Champions League, but we already knew that.
"He will help us in LaLiga and hopefully the Copa del Rey, but we must give him time to settle."