I booked my accommodation very late, for a one-month work-related stay in Singapore, and I was overall pleasantly surprised by the high quality service provided by Heritage Apartments.
Although the flat where I stayed was quite small, it was perfectly clean and ideally located in Chinatown, one of Singapore's most vibrant areas. Check-in was instructions were clear, so that moving in went very smoothly, and my hosts were kind enough to enquire about my stay several times throughout the month: I was even offered some fruits when they learned that I was feeling sick !
One point that may discourage some is that there is no window in the flat: if this is not a problem to you, I highly recommend Heritage Apartments for a flawless stay in Singapore !