What characteristic made the transistors better than the vacuum tubes?

• smaller
• less waste heat, ran cooler
• did not require high voltages to operate
• lower power consumption
• no filament/heater to burn out, more reliable
• not sensitive to shock or vibration
• both negative and positive current carrier versions available (tubes only have negative current carriers, electrons)

Unfortunately early junction transistors only worked at audio frequencies, and thus could not be used to build radiOS or computers.