The city offers all types of properties (for rent and for sale, so it is important you know what is on offer:
Khmer-style shophouses are common in Phnom Penh, usually found in 3-4 story terraces and typically long and narrow. Entrances are at the front or rear and side walls have no windows. Rear access can be un-nerving for westerners.
Renovated shophouses are less common but offer local experience + western comfort with new floors, additional windows, contemporary lighting, modern furnishings, hot water and so on.
Western apartments are found in low and high-rise towers. They tend to have more amenities, be new, have varied floor plans, windows in all rooms and plenty of natural light and air circulation.
Condos / serviced apartments are generally top-notch with western layout, natural light, city views, modern kitchens and bathrooms.