I stayed here last year with colleagues during a business trip. It wouldn't necessarily be rated as highly if it was put up against hotels in more touristy areas but it's a very pleasant place to stay in the area. On the first part of the trip we stayed in the cheaper inner rooms downstairs which have no windows to the outside (only into the corridor) which were clean & functional but not what I'd recommend for a romantic getaway as they are fairly basic. We stayed there again at the end of the trip, in the middle price rooms upstairs where you get a window to the outside world and a table & chairs outside the room. If I remember rightly there was hot water too in both rooms, the showers had a decent flow of water too which was a bonus (rather than the dribble from a pipe that you sometimes get) so we were happy with the general standards. The food was decent and the view from the restaurant veranda at the back is lovely, particularly at sunset. It overlooks Mansinam Island & the Arfak Mountains. We had access to a car through our work so we could get around but I'm not sure what the options for getting into town are if you have no access to a car other than taxis from reception.
The staff were lovely. We needed to use the wifi which was a bit ropy at times, slow or not working (we often had to ask for it to be switched off then on again to get it working but the staff were happy to oblige). We used it sitting in reception. This is something I'm guessing will improve in the coming years though.
We'll be returning to Manokwari later this year and will be staying in the Mansinam again. We'll probably book the cheaper rooms again as we only need a base & the outside areas are pleasant enough to sit at.