I haven't, no. But as far as I can tell from the documentation, it looks more like an alternative to stgit (with a similar lack of history or collaboration support)?
What you get is git-styled patch-series development. Branches on branches where each branch maintains history of the feature.
A git-spice workflow is compatible with GitHub style PRs where a PR depends depends on another PR.
Or pair git-spice with format-patch you can share with developers who prefer patch files. Or take patches from someone and import each patch as a branch, then let git-spice track the stack position.