When I think about Finnishness the first things that comes to mind are the dark and cold winters, short (but really great) summers and the sauna which almost every Finn loves. There is a LOT of lakes and forest too, so nature is a big part of Finnishness in my opinion.
Many foreigners think that Finns are really quiet, shy and reserved people which is partly true for many Finnish people, but once you get close with them they are loyal and pretty outgoing people. Personally I really like Finland and the Finnish people. I have travelled to many countries and to me Finns are pretty straight forward and honest compared to many cultures, which I really enjoy.
Finnish people also have this proudness of being Finnish and I think it has a lot to do with the history and the small population. In my opinion Finnish people have many reasons to be proud because it is a really clean, safe and equal country.