Quite a lot of work went into it. It is designed for 10k insertion cycles. 2x stronger to wrenching forces than micro, and it is designed so the cables fail, not the machine side connector (because once factories get up to speed have similar costs to USB micro cables now at least for dumb cables). Have a slide deck as a pdf if you want more details:

https://intel.lanyonevents.com/sf14/connect/fileDownload/ses...