At first glance it seems to be much simpler, less complex, and therefore less features than Vagrant. Depending on your requirements, Vagrant may be a better option, but for me Multipass looks great.

All that is missing for me is a active library of machine images like vagrant cloud. That would be amazing!

Looks like it supports launching custom images, but you'd need to build up your own library of images.

https://multipass.run/docs/launch-command