Pros and Cons of a Retirement Plan:

Pros:

Larger Tax Savings than a Defined Contribution plan.
Tax credits available for employers with at least one "rank & file" employee.
Tax-deferred growth of plan assets.
Can make up for lost time.
Structured path to building a retirement nest egg.
Can invest plan assets in a number of different avenues (i.e., mutual funds, stocks & bonds, real estate, start-ups, precious metals, etc.).
Retention of valuable employees by providing retirement benefits to employees.

Cons:

Mandatory contributions each year.
If plan assets incur losses, larger contributions are required in order to make up the difference.
Most DB plans must be covered by the Pension Benefit Guarantee Corporation (PBGC), which adds complexity and extra costs (i.e. $105 per plan participant, per year).
Annual reporting requirements (i.e., Form 5500 filing with IRS).
Administratively complex and cost money to set up & maintain.
Shutting down a DB plan can take several months (especially for plans covered by the PBGC).
Eventually retirement benefits are taxable.

Defined Benefit Plan:

Pros:

Flexible annual contributions.
Tax credits available for employers with at least one "rank & file" employee.
Tax-deferred growth of plan assets.
Can choose between pre-tax and after-tax (i.e., Roth) deferrals.
Structured path to building a retirement nest egg
Retention of valuable employees through company matching and/or discretionary employer contributions.

Cons:

Smaller Tax Savings than a Defined Benefit plan.
Some employer contributions are mandatory if plan is not Safe Harbor and/or is Top Heavy.
Annual reporting requirements (i.e., Form 5500 filing with IRS).
Administratively complex and cost money to set up & maintain
Eventually retirement benefits are taxable.