Feature-wise, it's about 3 years behind the features in ES. Although you have to pay for the higher tiers in ES, there's a much richer feature set. The Elastic cloud offering is much nicer than the AWS hosted version, for a similar price.
PfSalter, are you able to quantify what is nicer and improved about the elastic-hosted version?
In my experience, OpenSearch remains largely interchangeable with ES and has been a relative pleasure to integrate and use.
[1] https://opensearch.org/blog/technical-posts/2021/07/how-to-u... [2] https://github.com/elastic/elasticsearch/issues/74057