I have flown a few times now with RJ and the flight experience has always been positive. My only reservations are with Amman airport if travelling Y. Their crown class check in is great there.

During the early days of RJ with OW there used to be an issue in being credited with BA miles/points. This problem did not occur on my last two occasions.

At LHR RJ uses the BA lounge. So no difference in this aspect from a BA flight.

For those collecting tier points RJ of course would offer twice the amount for a flight to the Asia Pacific region. In fact last time I needed to fly from KUL to BKK and ended up netting 520 tier points for the LHR-KUL-BKK-LHR itinerary.

In fact I did stop in AMM on the way back and took a quick tour to Petra, Aqaba and the Dead Sea.