I stayed at hotel vondel for a business trip recently and enjoyed the location very much as it's close to the office and my old flat when I lived in the city so I know the public transport and area very well.
I liked the idea of the room, such as the modern amenities, decent sized rain shower, and the tall bed. However, the cleanliness level was not up to par. I wasn't as bothered on the first night by the random stains and marks on the floor and chair because these things happen. As long as the bed is clean, I am happy enough. However even the bed was so so! The second night I figured they wouldn't have changed the sheets, but they had, and replaced them with a pair of stained blue/black sheets with moldy specks and these VERY large and noticeable stains were right near where my shoulder and head would go- and yes, even below the pillow so it's not like I could just cover it with the pillow. It was late when I got in, so I just threw a towel over all of it, but I felt so itchy while I slept and couldn't get a restful night of sleep as I couldn't figure out what the stains were and felt icky all night. I was also eaten alive by mosquitos despite keeping the windows closed... and had to try and hunt them down each night before bed. Amsterdam is a mosquito-y city in the summer, trust me, this is no surprise to me. But with AC in the room, why were the windows getting opened at all?? I had to go to a business meeting with my eyelid swollen as one got me square on the face while I slept.
Everything else seemed fine though- staff was really nice. Again, it has the potential to be even better if they'd go in and do a few updates/clean some things up.