We stayed in City Apartments June 2014 for 4 nights. It was me, my husband and our 2 boys (9 and 12). We were touring Nordic countries for 2 weeks on a family vacation. We got the "Tower Suite" that has a main living floor and a bedroom suite up a spiral staircase. It came with a modern kitchen and included a sauna which was a fun extra. In the bedroom suite there's a German style bed (2 beds put together) that sleeps 2 and a pull out couch that can sleep 2 more. We ended up taking the bedding and mattress pads from the pull out and put them downstairs for the boys to sleep on. It was a bit campy but the boys made comfortable beds on the couches/floor and slept well.
The apartment was well stocked, very clean and there was a lot of space. We liked being able to do a quick breakfast in the apartment and were also able to bring in some basic dinners to have in the apartment. That was a nice break from eating out all the time and saved a bit of $. Also the pricing for the suite was a good deal compared to getting something like 2 adjoining rooms for the 4 of us in a hotel.
The location is AWESOME, very close to the train station, the Cathedrals, the Market Square and Esplande. In short all of the areas tourists are likely to want to visit in Helsinki. Several restaurants and supermarkets in easy walking distance. The staff were very pleasant and helpful. They even have tourist brochures and maps.
Overall we thought this worked well for us and would recommend it for a family stay in Helsinki.