We stayed at The Collector for 6 nights (28th April - 4th May) for our firt visit to Amsterdam. Sadly we didn't meet Karel as he was on vacation. However Fauzan was there to greet us on our arrival with a big smile. We didn't see much of him for the whole stay, as we had no reason to, but he was always available.
The room was the "Clock Room" at the front. Although overlooking the main road it wasn't noisy, and we used to sit on the balcony watching the world go by. An excellent asset to the room. The room itself was very large with en-suite bathroom which was a comfortable size, not small like other B&B's. I cannot remember the last time I have slept so well or for as long. The bed was so comfortable.
The location is excellent as others have said. A few minutes stroll and you are on the Museumplein, with the Concertbeouw and all the major museums. Outside The Collector is the tram stop, and just along the street is the bus stop for the Schiphol Airport Bus 197.
I think everything that can be said about The Collector has already been written, but feel free to contact me if you want any more info. I know people always say they will return to places, but with Amsterdam being such a fantastic city we definitely will be, and after this stay there is only one place we would stay. The Collector.