Over the moon that we've got him. That's a big coup for Arsenal, because he was being courted by some of the biggest clubs in Europe. So firstly a lot of credit goes to Emery/Sanllehi/Edu for getting this one done.
It remains to be seen how he adapts to the Prem, so he might need a few weeks/months to bed in. So I will give him until Christmas before we can really judge how it's going to work out. But given we've paid £72m for him you'd expect results. So I'd say a successful first season for him would be double figures in both goals and assists.