The digital crown now features haptic feedback, while the speaker is now 50 percent louder (which is great for Siri feedback). The microphone has been moved to the opposite side of the device to keep it away from the speaker (to cut down on echo). The back of the device is now made out of a ceramic material, which allows for better reception for the GPS and cellular radios.
There's a new S4 SoC running the show, with a dual-core 64-bit processor that is up to 2x faster than the processor in the Series 3. There a next generation accelerometer gyroscope, which can now detect a fall (if you slip off a platform or trip on a curb, for example). If it detects a fall, it will prompt you to call 911 if you need assistance. If you're immobile for more than a minute, it will automatically dial emergency services for you.
Apple Watch Series 4 can detect if you have a low heart rate (which can be a sign of serious health problems), and it can now screen your heart rhythms for AFib. It also has an electrocardiogram (ECG), making the Series 4 the first over-the-counter ECG product offered to consumers. The ECG works by placing your finger on the digital crown, and within 30 seconds, you'll receive a heart rhythm classification. All readings are stored in the Health app, which you can share with your doctor. The ECG has even received clearance from the FDA.
Apple Watch Series 4 will be available in aluminum and stainless-steel finishes in both GPS and GPS + Cellular configurations. Apple Watch Series 4 with GPS will start at $399, while the GPS + Cellular configuration will be available starting from $499. It will be available for pre-order starting this Friday and will be widely available on September 17th.