As the price is for the apartment, there is no extra cost. Moreover, there are great savings on the incidental extras - you pay supermarket prices for your food and drink. Even phone charges tend to be lower than those in hotels. The number of bathrooms in the larger apartments may vary, so be sure to ask at the time of booking. They also contain full cooking utensils, crockery and cutlery.
Maid service is provided either two, five or seven times a week.
Most apartment buildings have a 24-hour concierge desk. While some apartments do have restaurants and room service, the majority do not. That is how they keep their overheads low and charge less for the room. Yes, possibly even more so than a hotel. Most apartments buildings have discreet entrance areas.