San Francisco, Oakland and 1-2 other Bay Area cities have had this for a while. I think it works well, and the electorate and politicians are getting used to it.

The implementation, at least here in Oakland, is a bit clunky. When there are only two candidates, they still let you pick your first, second and third choice...

Having it at state level opens things up to a whole different level. Now a popular and/or centrist third party candidate can realistically get elected as US senator, and that's real power.