He's a very good signing, and I think he is an upgrade over Giroud. Plus having an attack of him, Ozil, Mkhitaryan, and Lacazette... That's dangerous. Throw in Iwobi, Welbeck, Ramsey, and Wilshire Arsenal should put the ball in the net a lot.
However, The back 3, or 4, or 5 whatever it may be...