I did the intermediate exam a few years ago. I was, to be honest, more advanced than needed and I'm probably more experienced than most of the people taking the advanced exam, but anyway, I did it.
The way it worked was that you were allocated a time (in my case 9.30 a.m.) and 1 hour beforehand you were sent the article you had to read and the topics for the "Pwnc llosg" (Burning issue) and the monologue. The article was about seagulls and the problems they cause and the burning issue topics (for which you had to give both sides of the argument) were i) the NHS and ii) Newspapers and TV news tells lies. I chose the second option and went for a rather nuanced argument that even the evil tabloids don't tell outright lies in the articles, but they DO lie with their headlines. The monologue topics were i) the first time you moved away from home or ii) attending an eisteddfod or other festival. I chose ii) and talked about attending the SF WorldCon in Dublin in 2019.
Overall I think it went OK. I don't need the qualification, but signing up for the exam did motivate me to study and practise harder than I otherwise would have done. As it was free, and the 3 practice tutorials to prepare for the exam were also free, it was a real bargain to get several hours of speaking practice.
I was completely wiped out after the exam though and did virtually nothing for the rest of the day. I'm obviously getting too old for 90 minutes of intense mental activity!
Today has been a day of practical things, like the top-up shop in the Co-op and a couple of phone calls with friends this morning. I now need to work out what to focus on next, now the exam is over and the Welsh course ends next week.