Also just had an excellent award stay at the Reisen with my wife.
As a Globalist, I was pre-upgraded to a Nordic King (with a sauna) which we were very excited for, as we both love sauna. When I chatted with the reception agent (Eric, who was outstanding, I might add), mentioned that there was no Nordic Suite upgrade available, though he did have a Sea View Suite available, and proactively offered to show us both rooms.... Nordic King & Sea View Suite.
The Nordic King was on a high floor but without much of a view, was a bit small but still would have been great given the in-room sauna.
The Sea View Suite (#108) was on the second floor of the hotel, had huge taller windows than the other floors, which opened (this was key since the rooms have no air conditioning, and it was hot during out stay) with gorgeous views of the water. Even though the room had no sauna, we opted for the suite and absolutely loved it.
The hotel has a wonderful basement level spa with a huge sauna, rain showers, and amazing plunge pool. The plunge pool was plenty big and deep enough to dive into, swim, etc and was just cool enough to be refreshing after the sauna, but warm enough to enjoy at length without discomfort. Most plunge pools are freezing cold, this one was perfect.
As others noted, breakfast was great. The staff work hard as it was busy during our visit, so kudos to them. I was a little bummed that the hotel's craft cocktail bar was closed for seasonal renovation, but their lobby bar was more than sufficient and the bartenders skilled.
We loved the location, although it's a bit of a walk (18mins from Stockholm Central Train Station). For our departure, we opted to enjoy the spa/sauna as long as we could before heading to the airport (instead of walking to the train station), and had the front desk called us a taxi which was an even $68 USD to ARN airport in a Mercedes wagon with a courteous, professional driver.
Overall, we loved this hotel and I found it to be a wonderful value at only 15k points/night.