watches are retina OLED
some level of water resistance
WiFi + Bluetooth
motion, stability, light sensors
Target had a sale - I think it was Series 3, for $229, which if so, is a great price.
They still have Series 1 for $249+
but the rest of the prices are surprisingly high... even Target is carrying an $800 SKU.
Apple prices are mostly $300-700.
In Jan., there has been an a couple price tests at Target and Best Buy, a Series 3 at $229. (This despite the fact it is less than Target's stale Series 1 stock.)