The Borussia Dortmund striker's arrival is due to be confirmed today.
Last night, Wenger stated: "Yes, it is good news. We need people who can give us more offensive power.
"At the moment, we aren't enough going forward and I am convinced he will give us that.
"He has a big challenge in front of him. He wants to do well in the Premier League.
"It is absolutely good news for us.
"His pace, his finishing. The quality of his runs. His huge physical capacity, that will be important in the Premier League."