Yes, for basic non-custom v10 sites. However, expect some issues to arise in the process. And please report those issues to the tracker.

For v10 sites with non-bundled addons or customisations, upgrading to v11 will likely break the site until you update the non-bundled addons or temporarily remove the customisations.

We aim to have the upgrader fully functional for a large majority of types of sites and for sites using non-bundled addons by the time version 11 reaches release candidate stage.

We do not recommend upgrading production v10 sites at this time until v11 reaches stable.