A couple of years ago, I flew from RIC to SIN using frequent flier miles from Delta. Delta was to provide the US domestic portion of the trip, and Singapore was to provide the international portion. I had reservations on SQ from JFK-FRA-SIN going and SIN-AMS-JFK returning. Shortly before my trip, I was notified that my SQ segment from AMS-JFK was discontinued on the day of the week I was flying, and the only way they could get me back would be to leave Singapore just a couple of days after I got there, then wait several days in New York until my originally scheduled Delta flight would take me the rest of the way home. This was totally unacceptable to me. What was the point of going all the way to Singapore for just a couple of days? Singapore Airlines told me there was nothing they could do. They couldn't take me any farther than AMS, and I would have to find alternate transportation from AMS-JFK. I called Delta since I was using Delta miles, but they said they could do nothing, since it was a Singapore Airlines award. After going back and forth with SQ and DL on the phone, I finally got to talk with a sympathetic customer service agent who got permission from higher up for Delta to fly me from AMS-JFK at no charge. So it ended up working out fine, thanks to Delta.
On that same trip, when I arrived in SIN, my "indestructable" American Tourister suitcase came down the baggage conveyor smashed. The metal band that goes around it was bent in on both sides so that a baggage agent needed a crowbar to get it open. Singapore agreed to pick it up at my hotel, repair it, and return it to me at my hotel, which they did. Then they damaged it again. I had a 24 hour layover in AMS, and when my suitcase came down the conveyor, the bottom was smashed in. Singapore Airlines said they would repair it but I had to take it to the repair shop myself, which was not located in the airport. Since I only had one day in Amsterdam, I didn't want to spend it looking for and waiting around a baggage repair shop, so I didn't accept this option. They told me I could wait until I got back to the US and get it repaired there, and they would pay. But when I got to my hotel in Amsterdam, I managed to punch it out myself and it looks close to normal. I have had that suitcase since 1980, and no airline has damaged it before or since.
One other thing. SQ does not permit advance seat assignments in economy. You have to take what's left when you check in.
Other than that, I thought SQ service was excellent inflight.