What is clinical assessment and why is it important?

What is clinical assessment and why is it important? What are your thoughts about the DSM (i.e., pros or cons)?

What is the DSM and why is it important?
The Diagnostic and Statistical Manual of Mental Disorders (DSM) is the handbook used by health care professionals in the United States and much of the world as the authoritative guide to the diagnosis of mental disorders. DSM contains descriptions, symptoms and other criteria for diagnosing mental disorders.
Why is clinical diagnosis and assessment important?
By having a clear accounting of the person’s symptoms and how they affect daily functioning, we can decide to what extent the individual is adversely affected. Assuming a treatment is needed, our second reason to engage in clinical assessment will be to determine what treatment will work best.