What are the operation and functionality advantages and limitation of plc?

we can demonstrate the advantages of plc by compare it versus classic control:  

1-Programming the PLC is easier than wiring realy control panel

2-PLC can be reprogrammed whereas conventional control panels must be rewired

3-PLC take less floor space than relay circuit for achiving the same function

4-reliability is greater than conventional control circuit

5-PLC can be connected to PC more easily

6-PLC is more safe than classic control

7-PLC can perform a greater variety of control function than relay control

8-PLC system can expand in future and do many modification more easily

the limitations are :

1-PLC is more complicated than classic control

2-need special experience to work with

plc is used for controlling any industrial operation . plc has ability for  doing any program . plc output has limited current