S K.
Yelp
This is a very nice hotel typical of non-chain European hotels. I stayed in a Comfort room, and I would absolutely recommend doing so for the slightly better space and facilities (according to the Web site).
The hotel is extremely clean. The breakfast spread is diverse and maintained well. (The breakfast area is also very elegant, with a few fake tree trunks on one side adding very much to the look.) The sauna is nice (but sadly, did not include birch branches!). The room provided quality Thann toiletries, including body lotion. This was also true of the sauna shower. The room included a robe and slippers for the sauna.
The main train station is only a 10-15 minute walk away. All of the main parts of central Helsinki are easy to get to (even by foot). There's plentiful public transit nearby: It's only two minutes from the closest entrance to the Kamppi metro/bus station and mall, including the very good K-Supermarket.
The hotel staff are helpful, friendly, and very responsive by email. A few small issues I reported were handled very quickly (though one never received a reply).
The Wifi is fast and has no login at all, which is very nice.
My only slight annoyance was that the hotel made a really big deal out of their "Finnish design", and yes, they do have a few Finnish furniture items. But these weren't particularly fancy ones. I suspect to most travelers, it would have been indistinguishable from a room furnished entirely at IKEA.
Overall, it was a great place to spend a few days, and I would return without hesitation.