Absolutely love Sakho.
He is a proper beast of a defender. From what I've seen so far, he's been great. The occasional wayward passes due to moments of nervousness can be forgiven, considering his age and the fact he's new here.
For example, look at Koscielny. He was a joke when he arrived at Arsenal. Prone to errors. Now he's easily one of the best central defenders in the League.
I think Sakho can surpass Koscielny.
I'd love to see a partnership of Sakho and Toure. Both beasts, and it would be the right balance of experience, imo. Toure, the veteran defender, looking after the new-comer, Sakho, and helping to mold him into greatness.