My husband, sister-in-law and I stayed in the ISIS apartment on the top floor. It was light spacious and had everything we needed. Anna and Jan (the owners) made us feel very welcome and made us a hot drink when we arrived! Help was always offered and given which made our stay really pleasant. It is definitely worth staying in Haarlem if you want to experience a different pace of life and have the excitement of Amsterdam only 15-20 minutes away by train. I really loved the local shops, cafes and restaurants and highly recommend using the bakery that is 2 doors away from ISIS.
If you are arriving at Schipol Airport, I would advise that you take the train to Haarlem via Amsterdam Centraal (approx €7) and then take a 10 minute taxi ride to Emmaplein (approx €7.50 - €10).