I just ran it.
It doesn't compare to firecalc. It doesn't allow for asset allocation issues. It doesn't allow for one time spending occurrences. (Like paying for college or a wedding). It limits other income sources - so if you have more than one pension, or rental income, etc... you have to combine them and hope for the best.
Here's the link if anyone else wants to look at it.
SmartMoney Retirement Planner - SmartMoney.com
Maybe I'm too gloomy - but I like to *plan* for worst case and hope for best case. And this calculator seems overly optimistic. If you relied on the results and it didn't turn out, you'd be hosed.