Yes, it is very good at that point in Arlanda but it can be very cold there even on some summer days too but it is excellent for viewing. Is there public transport to the area from the terminals?
Bromma, of course, is outstanding and on it's own makes Stockholm worth visiting. Bromma is fabulous - yes, you will see everything there in a day or two at the most but it is just wonderful.
Sweden is wonderful, full stop. It is okay to like aeroplanes in Sweden.