Don’t rent a subdivided apartment: the smallest legal rental unit is the original room as designed; kitchens, bathrooms, balconies must not be used for living

Cost: There’s no direct expense. The trade-off is that with the same budget, you’ll either have to live farther away or in a smaller space.
In plain terms: By regulation, the minimum rental unit is the original room as built. Kitchens, bathrooms, balconies, and basement storage areas cannot be used for living. If such a unit is found to be illegal, you may be forced to move out. Additionally, during the lease term, landlords cannot unilaterally raise rents at will.
Benefit: The rules are clear: the smallest legal rental unit is the original room, and it cannot be subdivided into multiple units for separate rentals. The minimum per-person living area must meet local legal standards. Kitchens, bathrooms, balconies, and basements cannot be rented out for occupancy. Landlords also cannot arbitrarily increase rents during a lease term.
Evidence grade: A
Sources:住房和城乡建设部 (2010). 商品房屋租赁管理办法（令第 6 号）第八条：「出租住房的，应当以原设计的房间为最小出租单位，人均租住建筑面积不得低于当地人民政府规定的最低标准。厨房、卫生间、阳台和地下储藏室不得出租供人员居住。」第九条：「出租人应当按照合同约定履行房屋的维修义务并确保房屋和室内设施安全……房屋租赁合同期内，出租人不得单方面随意提高租金水平。」http://www.gov.cn/gongbao/content/2011/content_1845070.htm
Notes: When illegal room subdivisions are identified, tenants bear the cost of moving out, and often cannot recover their security deposit or prepaid rent. Safety is also a concern: makeshift walls often block emergency exits, and overcrowding in a single unit leads to shared wiring. When viewing a property, check three things: whether any walls were added later, if the room has a window, and whether the electrical meter can handle the expected number of occupants.