The Basis wristwatch measures a variety of health factors, captures the information, and then processes and interprets it. It's one of the more comprehensive systems in this form factor.
For example, many products take a measure of heart rate. Some help count the steps a user takes during the course of a day. Others track calories. Basis Health And Heart measures heart rate, motion (using accelerometers), galvanic skin response, and skin and ambient temperature.
All of this data gets synced up to Basis (its "cloud service"), where the user can browse the information. Some of the data (motion and skin temperature, for example) gets interpreted as sleep; other data (motion and sweating, for instance) gets interpreted as exercise. The bottom line then is that this data isn't just interpreted individually, but taken and understood collectively.
The watch (and yes, it does tell time) uses a host of sensors to detect all of this, and it even includes an optical sensor that emits light into the skin at a particular frequency to determine heart rate.
There are some similarities to the much ballyhooed Jawbone Up, which was riddled with hardware problems shortly after it shipped. The idea is still a good one. The biggest problem with the Basis product is that the software side is completely browser-based. That works, but having that data in a smartphone app would also be good, especially for viewing the data offline, as so many products let users do.
At $199, it's not a bad deal.