We stayed in Marieke and Peter's beautiful houseboat mid Feb and I wouldn't hesitate to recommend if you are staying in Amsterdam.
Firstly the houseboat location was great, away from the real hustle and bustle so it was peaceful and quiet - but close enough to the touristy and night life that it was easy to get to. Tram links were also easy to navigate.
The houseboat itself was very clean, simply furnished and comfortable. The bed was soooo cosy and comfy. Despite being Feb and very cold. We at no point felt cold - it was easy to regulate temperature.
The shower was excellent (waterfall).
Marieke and Peter were welcoming, friendly and very helpful, providing excellent recommendations. We also arrived very late on our first night and Peter stayed up to greet us.
So please take it from us, if this option comes up in the days you are looking for, go for it. you won't regret it.