Never used it since it was only available in the US. Looks like additional countries were not added till Oct 2016, 11 years after it was first launched[0]

None of the companies I've worked for have used it AFAIK, despite them all using AWS. I think I've mostly ignored it as one of the niche AWS products that isn't relevant.

[0] https://blog.mturk.com/weve-made-it-easier-for-more-requeste...