This was the second site we visited on our tour through Finland. Generally speaking I've quite enjoyed industrial Heritage sites like those in Germany and England, and I quite enjoyed this one as well. The large main mill building is excellently preserved, and is apparently much as it was when the factory shut down in the 1960s.
The first stage of the mill tour involves watching a film that details the workflow of the mill, showing how the raw logs were eventually turned into cardboard and the like. It was quite cool to walk out of the presentation room into the factory proper, and see the exact same locations and machinery we'd just seen on the screen - a little jarring, but cool in its own small way.
Around the mill itself there's also the large owners house which is quite impressive, along with several other outbuildings of the mill. We spent a bit of time wandering the grounds, though the highlight was definitely the mill building. The cafe in one of the buildings had some tasty local Finnish specialties which we hungrily devoured!
My only real complaint with this site was that photos and videos weren't allowed inside! I'm really not sure why - there isn't delicate painting to be protected, no trade secrets, and it's definitely not crowded enough to be a crowd management issue either. Maybe they've had problems with people filming the tour guides? Either way, we found it strange and it made for a rather difficult video!