I have flown this 24+ hour route many times with many airlines for nearly 50 years.
I have flown Royal Brunei several times and they stand out as one of the best airlines I have travelled. The cabin crew are consistent in their level of service. Courteous,helpful, attentive, well groomed and proud of the airline they make something special. On the Australia to UK route I would rate RBA as a 9.5/10, and by comparison would rate BA and Qatar as 2/10, Singapore would get 6/10, Qantas nowadays 7/10, Emirates 7/10, JAL 9/10, United 8/10. The food is of a high standard and seems freshly prepared in comparison to many of the other carriers. The best thing with RBA is there is no fuss. They aren't an "over-rated" corporate monster of an airline who spend more on marketing than on their product, they are the real thing. Calm, and interested primarily in the passengers. Legroom on their 787 aircraft is way more than offered on most carriers, the seats have a decent recline. Their 9 abreast 787 layout seems much less cramped than that of their competitors, and there is a real sense of cleanliness and calmness over the whole event of travel with them.
The two stops makes a huge difference to the tolerability of the flight. 3x7 hour flight legs is perfect. The one-stop flights with the 15 hour leg most carriers offer is pure misery. You might arrive an hour earlier, but you feel so much worse. Give me two stops any day. Dubai is a big airport but well managed for transit passengers. I personally love the Brunei stop. The airport is calm and well ordered and a very manageable size. I recently transited through Doha airport which ranks as the worst and the most overcrowded I have encountered. It was utter hell. The one thing which is a downgrade at Brunei: in the past you disembarked your first flight directly into the transit hall and only went through security at the gate as you boarded your next flight. Nowadays, you disembark your first flight and have to go through security to re-enter the transit/departure hall, a process which takes up valuable time at the start of your transit. I have a workaround. I go straight to the arrivals hall, clear immigration on a transit visa and go landside, then re-enter departures through that security channel which is way quicker - usually no one else there. It also gives me a quick break from being locked in planes and airport buildings, as I go for a short walk outside and take in the gardens and vegetation which surrounds the airport. For anyone who has read complaints about the secondary security at the gate to check for liquids, this is an imposition initiated by the Australian Government and not Royal Brunei Airlines. Signage explaining this are displayed through the terminal. Simple thing is, read the signs and don't buy drinks to take on the aircraft. They have water and all manner of soft drinks on board.
I have flown Royal Brunei between the UK and Australia at least 6 times, and I cannot fault them. I am extremely fussy, and just old enough to remember the days when Economy Class was much the same as what we now call Premium Economy. But while other airlines seem set on destroying the things which make international travel so special, Royal Brunei have maintained some of those special values unlike other high profile airlines who spend all of their resources telling you how good they are without being very good at all. I have always found Royal Brunei to be in a league of their own, something of a boutique operation who go to great lengths to look after you in every way possible.