I flew ARN-CPH-LAX and EWR-OSL-ARN recently and both flights were highly enjoyable. Food was great (love the salmon), internet stable, crew very friendly and IFE seemed decent. Especially in row 1 on the A350s SK C is amazing. I think I haven't had such a seamless trip in quite some time. In CPH I walked to the gate with impeccable timing and was able to walk on to the plane as one of the first pax, in LAX customs with Global Entry took a mere 20 seconds, my bags arrived within minutes of me arriving at the baggage belt and I was out of the airport in less than 15 minutes. This trip really reminded me of what travelling is all about and how great and enjoyable it can be.

In EWR I did arrive as one of the last (just at the same time as the crew). Tipp: Don't try and take the Airport Express Bus to Newark. I ended up sharing an uber with some of the people waiting in line for the airport express that were just left there because the bus was already full. I nearly missed the flight...
The SK lounge in EWR is rather dreadful, the LH Sen lounge is better and when I visited, it was completely empty. It would be really cool if SK and LHG would decide and operate their lounges together, I'm sure they could do some nice stuff, with one lounge being for C and the other for *G, maybe even offering à la carte dining with the combined budgets like the US Polaris lounge? Yeah, I'm dreaming again...
Anyway, the A321LR I took to OSL was a really cool experience too and having gotten a throne seat I had a pretty good time as well. The seat is a little narrower (Vantage on the A321 vs. Vantage XL on the A330/A350), but still enjoyable. Dinner was nice as well and service friendly. Overall, a really good flight.
Immigration in OSL wasn't that great as there was only a line for NO or foreign passports, or at least the staff there was blocking the EEA line so I ended up behind some people that were questioned for a good 30minutes. Also having to reclear security in OSL isn't that great, but I digress.

SAS Business is a great deal for the great service you get, especially looking at the cheap tickets they often offer. I've decided to move more of my travels to SK, instead of LH/LX F (which has become insanely expensive), I'll fly SK C to NYC next year for example. And some flights to Tokyo will hopefully also end up on SK if their schedule sticks.
I did pretty much enjoy SK C just as much as LX/LH F tbh, the difference (at least for me) isn't huge. Sure, LH/LX F offer amazing ground service and better hard and soft product on board, but for me the difference really wasn't that great to how much I enjoyed my SK C flight to LAX.