To recap: Android O is mostly an under-the-hood update that improves loading times, battery life and other subtler aspects of smartphone use. There are a handful of conspicuous changes, though, such as notification dots on app icons (with pop-up notification windows), support for lightweight machine learning on-device and a picture-in-picture mode.
As with past previews, though, you will need to have the right device to give this a look. You'll need a Nexus 5X, Nexus 6P, Nexus Player or Pixel device to use the beta, and it's safe to assume that these will be among the first in line for the polished Android O release. While a handful of third-party Android phone makers are quick to offer upgrades, it's likely that you'll be waiting at least a few months before you see O reach third-party Android hardware in earnest.