The former Everton winger made an impact off the bench at Newcastle on Wednesday night on his debut and Barnes said the 30-year-old had settled in well.
"Aaron's been fantastic since he came in, he's trained for a few days and he's getting to know the lads a bit more," he said.
"He's settled in right away."
Meanwhile, manager Sean Dyche has explained not signing a new defender in January.
"We can't really buy stopgaps, I don't think that helps the club," he said.
“It's difficult because you have to get the job done. We are in a favourable position but the player coming in has to be someone who can add to the group or push the group going forward in the future."