Okay, I had my wife go through the process. She has seen very little of Discourse and has never used a discussion site running Discourse. She only knows what I've shown her via the plugins I've created and features I've worked on.
It took her 2 minutes and 30 seconds to notice the pinging notification
Once she found it, she didn't like that the first interaction was to respond with a word that didn't meet the minimum characters limit. She ultimately repeated unicorns twice, but maybe changing the words to phrases such as "I like unicorns", "I like ninjas", and "I like monkeys" would solve this.
She had a hard time finding the bookmark icon. The flag step gives the user a hint that it is hidden behind the "..." (show more) button, but the bookmark step does not provide such a hint.
Lastly, for the quote a reply, she didn't like she wasn't instructed to also type a response. She followed it to the letter, quoted it, and hit reply, only to be told "post cannot be empty." She then proceeded to argue with me that it isn't empty, it has a quote (thanks for that! ). Maybe adding "And tell me why you like that quote" would help ease any pain with that step.
Everything else she had zero trouble with, including the flag option (since it hinted at it being behind "..."). I literally blinked and she was already past that step!
Oh yeah, she was quick on the draw with Search too. She entered "bunny" and pressed enter immediately, which took her to the advanced search. Confused, she looked at me and and said "I did something wrong?", to which I nodded, she hit back, re-read it, and then slowed herself down to do the steps again, hesitantly clicking the "In this topic" checkbox.
Once she did that though, clicking the first search result was rewarding and she found that intuitive.