What has changed?
One of the biggest patches in this update included a fix for the wifi that was allowing users to get to the home screen while in activation lock. This would prevent users from being able to entirely get around the activation lock.
Contacts received a patch that prevented “Processing a maliciously crafted contact card (that) may lead to unexpected application termination.” Basically, a contact card could be created in a malicious manner to be turned into an executable bit of code that would kill applications, start applications, or potentially take data from your iPhone.
Kernel and Webkits
Apple made several security improvements to the kernel of IOS 10.2. This, along with the improvements to the webkits included in IOS, all were focused on improving memory management.
These were the most exciting of the updates and most of them are targeted at our security as users of the device. Apple does a great job of maintaining their devices and pushing new security updates out regularly.