Personal experience is that AWS elasticsearch has often been missing some really useful stuff, index rebalancing, some of the utility endpoints that avoid me having to spend forever rebuilding indexes, etc. I'd be a little spooked to run something really huge and customer-facing (maybe it's possible and I'm a n00b, but for the money we pay, it should be n00b friendly).

It's always great (really, it was quite easy to get started and usually works) until it's not (a couple times have had indexes break, or had to reindex to a fresh cluster to fix balancing problems).

I'm sure LOTS of people use aws elasticsearch for big, user-facing stuff, but I often feel you'd be better off managing it yourself if it were truly critical.