Having stayed at Radisson Red twice last month I thought some updated info and photos might be useful.
As already mentioned there is a covered walkway between the terminal and the hotel. The start of the walkway near the terminal was a little icy when I arrived for my first stay but it took me 6 minutes to walk to the hotel entrance with luggage. The last 10-15 metres before the hotel entrance is not covered.
Standard rooms are perfectly fine for one person with a king bed, a coffee machine, a stocked fridge (didn’t check the price list), a safe, an iron and ironing board. The hotel has obviously been refurbished since 2020. There are self check-in/check-out machines by the reception. I used one for checking out but self check-in may not work if they need to see your ID/passport. There is a gym though I didn’t use it.
I had one light evening meal and one breakfast in the restaurant during my two stays. Food price wasn’t too exorbitant if you avoided or limited the amount of alcoholic drinks. Breakfast is not sumptuous but fine especially if you like Scandinavian breakfast with lots of pickled and smoked fish. I don’t have any status but members get a 10% discount in the restaurant.
I haven’t stayed at Radisson Blu OSL and can’t compare the two but Radisson Red is perfectly fine for me for an overnight stay between flights.
Hotel entrance after snow

Hotel entrance in better weather

Standard king bedroom

Entrance to the restaurant

Restaurant

Restaurant