I've gotten braver about eating at the cafeteria downstairs in my work building. It seemed like such an impenetrable Finnish social custom for so long: those lines and all those beverages and the clean-up routine. It was a SYSTEM. And I was an outsider. I did not grow up with an institutionalized hot lunch, after all.
But over the past month I've eaten there a couple of times and I feel like I've figured it out. And it's great! I definitely see why hot lunches are so popular even for adults in Finland. It helps that the students can get a full meal for €2.60, thanks to Finland's generous student benefit. For us lowly staff, it's €5.80. (That's still a good deal, considering the amount of food - for similar meals off-campus, I'd have to pay around €9-10.) Visitors pay €6.50.
The menu changes every day and there are always 2-4 options for a main dish, including one vegetarian dish. (The menu is often posted here in English - have a look!)
The beverages on offer every day are water, milk, piimä (cultured buttermilk), concentrated juice that you then dilute with water on your own, and low-alcohol beer in open pitchers. There is always salad and usually some form of potatoes as well, in addition to whatever main dish options are available. And of course, there is always sliced bread and butter - several kinds of loaves to choose from.
I still bring my own lunch from home the vast majority of the time, but on less-busy days, it's nice to have a big hot meal at work.