In addition to the obvious life-hospitable factors, such as a temperature suitable for liquid water and a suitably-sized sun, there are many more factors required for a planet to be fit for human-like intelligent life (with more factors likely to be discovered):

Suitable gravity for atmosphere, with appropriate pressure, to retain oxygen and water vapor but not hydrogen; suitable axis rotation rate; appropriate tilt of planet axis for seasons; suitable orbital distance from star to prevent tidal locking; magnetic field from planet molten core to shield atmosphere from cosmic radiation; sufficient planetary plate tectonics for crustal mineral recycling; suitable distribution and shape of continents to sustain deep ocean currents; sufficient actinide radioisotopes in planet interior for decay heat; suitably-sized moon to create needed tides and stabilize planet rotation; giant outer gas planets to prevent large asteroids and comets from frequent collisions with planet; suburban galaxy location providing sufficient distance from recent supernovas; far enough away from gravitational disturbances by higher density of stars in inner area of galaxy; only minor orbital variations caused by small chaotic gravitational interactions between nearby planets.

With these factors the number of planets in our galaxy capable of sustaining human life is much smaller than the media and grant-seeking astronomers imply in their articles. The estimated probable number is likely very close to the experimentally known value of one.