Lots of live Commerce 2 sites were actively and successfully selling products to people long before the official launch on September 20th. We ourselves were among the early adopters taking advantage of the new functionality available in Drupal 8. But as with any new-and-not-fully-tested technology, there were the inevitable growing pains: missing functionality, bugs, etc. Fortunately, most of those issues are now in the past.
A few core modules that were buggy but are solid now:
As an added bonus, the Commerce Shipping module that Acro Media helped develop received a full stable release alongside Commerce 2 (which is especially cool when you remember that Commerce 1 launched with no shipping functionality at all). Commerce Shipping features a much improved API and includes support for UPS and FedEx, with USPS to follow shortly.
Acro Media and other community members have been working on a few other associated modules to go along with the Commerce 2 launch. Here are the details:
A cool new Composer based Commerce Kickstart installer is also available! It represents a great improvement over the original Commerce Kickstart and should be easier for everyone to use. You can find that here.
TLDR: The fully supported, stable release of Commerce 2 is live and has lots of cool stuff with it. If you were hesitant to use it to build sites before, you most certainly can go ahead now.