While the Artemis only came in one size, the Poseidon can be customized to sizes both big and small, and the orientation can be flipped to either landscape or vertical. You can also choose different lighting setups, different color frames, and more. From there, the mirror is made up of multiple modules that you can swap in or out, much like a build-your-own PC.
There are options for a multitouch surface, an ambient light sensor, a touchless frame where you hover your fingers above the glass, different color LEDs (there's a gesture option where you can change lights by waving your hand in front of the mirror) and more. It even comes with a motherboard with a Qualcomm chipset, USB, WiFi and Ethernet, which definitely makes it more like a computer with a mirror. There's also a camera, which is useful for facial recognition, various AR applications and detecting your posture. If you're concerned about privacy, the camera does have a manual lens cover. CareOS also told us that all of the information is stored locally and not shared on the cloud.
Aside from all of these modular components, the Poseidon is very similar to the Artemis. As mentioned, it runs CareOS, a smart mirror platform with augmented reality and connected components. You can use it to swap out hair styles, try on different beauty products (there are even video tutorials), and check to see if that random beauty mark is something to be worried about. It can be connected to HealthKit or Google Fit so you can see your activity levels on the screen as well as smart thermostats so you can adjust the temperature from your bathroom mirror. The company has also partnered with Mateo, which offers a smart bathroom mat that doubles as a scale, so you can monitor your weight as well.
The big downside to it? It's insanely expensive at $3,000 to $6,000 a pop (the price varies so wildly because it's dependent on which modules you decide to add). CareOS said that the mirror is for both consumers and retail -- it's working on providing it to select Wella beauty salons at the moment -- but I can't see this as something that you or me would buy. That is, unless you just have a ton of cash to burn.