When you are in a period of deflation people hold off buying goods and services on the sure knowledge that if they wait a while those goods will be available at a lower price. This then decreases trade and the flow of money which results in people lowering prices yet further to attract trade and you can then end up in a deflationary spiral. Is it worse than inflation? Yes, all economies depend on a certain level of inflation. The problems with inflation arise when you enter a period of hyperinflation as was seen recently in Zimbabwe and very famously in the inter war period in Germany where people burnt bank notes to keep warm as they were so worthless in comparison to wood and coal as fuel.