The major drawbacks and problems of the deliberative paradigm are its costs and portability/modularity

The costs of the deliberative paradigm, both computational and memory related, are too high as planning requires many complex calculations:

• Getting a plan for a real environment can be very slow, as it requires a lot of computation.
• Getting a plan for a real environment requires a lot of memory in the controller.
• Getting a plan for a real environment requires that the world model is accurate, so it has to be updated, which requires more time.
• Executing such a complex plan is not a trivial task.

There are other problems, however, that also have to be taken in consideration:

• The sense and act phases are always disconnected.
• There is a heavy dependence on the world model. Changes on the environment require an update, which makes the whole process more expensive.
• The execution of the plan makes the robot more vulnerable to the uncertainty of the environment.