Definitely targeted at the enterprise, but it's entirely possible to provision and operate a single instance without any kind of enterprise-level agreement.
Worked on Workspaces at AWS for about a year, on the software clients in particular. I think their product has potential but for the moment is limited by some underlying technology decisions made in the interest of a quicker go-to-market.
I would not be surprised if at some point soon their underlying tech became all first-party and we saw some significant improvement. There are plenty of resources throughout AWS that with some work could be composed into a better stack than the 3P pieces and protocols they use currently.
I don't think I've disclosed anything here that isn't already public knowledge, past my own wild speculation based on zero knowledge of internal workings since my departure. If anyone has any questions that I can answer without endangering myself to NDA issues, I'd be glad to answer about Workspaces.
I think it's a great product for those who benefit from it; I ended up leaving the team because while the technological challenges were interesting, I couldn't put myself in any potential users' shoes, and therefore really couldn't drum up much organic passion of my own.