Discourse searching certainly has all of the functionality you’d expect it to (searching by poster, age, recently-posted to lastly-posted, etc), but all of those are taken advantage of through keywords in the search bar. I haven’t been able to memorize them all yet, so I frequently find myself looking at the “Search Help” in order to find what I want.
The problem with this is that you don’t have access to the search bar while Search Help is open. The Discourse forum I use is only visible by members, so bots can’t index posts for a Google search, and I have to use the normal search bar. I might want to search for a post by a certain user, look up what the keyword is in Search Help, close search Help, find that I also want to search by order, have to look up what that keyword is, close Search Help, and repeat every time I search for something. This isn’t very plesant and it’s not very friendly to new users – it’d be nice if a normal search bar was placed on Search Help at the very least to save the need to repeatedly open/close Search Help, but new users would probably find an “Advanced Search” page most helpful. Here’s an example from the forum software I was previously using before switching to Discourse:
All of the search parameters are controlled through dropdowns and textboxes that are easy to interact with and there aren’t any keywords to memorize. Keywords are great for power users, but your average member might prefer a GUI over keywords (maybe turn the full page search into this?)