"With a more aggressive geometric shrinkage, this process offers 2X logic density than its 16nm predecessor, along with ~15% faster speed and ~35% less power consumption. This process continues leveraging the revolutionary FinFET advantages to help customers achieve best density and power efficiency." http://www.tsmc.com/english/dedicatedFoundry/technology/10nm.htm
The 10nm is not as great as marketing material would lead you to believe. There is reason why many companies skip 10nm alltogether. Let's get back to this once we see other vendors produce 10nm socs and have comparisons on how apple compares.