I've been around since Lotus 1.0, and worked in financial and engineering firms. I've seen cases where spreadsheets have been the right answer for knowledgeable and relativity sophisticated users, either to build a quick model or as a front-end, and cases where the result is an unauditable mess. Lots of oops when say accounting people don't understand say the math of partial-period NPVs, or are so innumerate that an obviously wrong result looks fine to them. Without the review process that should go along with production code, sometimes you get lucky, sometimes you don't. It all comes down to who is using the tool, I guess.