Do you consider SIEM systems sufficient for information assurance?

In your own words: provide and explain 3 advantages and 3 disadvantages of using SIEM systems for security in business environments. Do you consider SIEM systems sufficient for information assurance? Explain why or why not.
Which part of information assurance is the most critical: privacy, regulatory and standards compliance, auditing, business continuity, or disaster recovery? Explain why in your own words.