Deflation is rare but has occurred occasionally through history. As experience with it is very limited and much of common experience fails to apply, many of its features are counterintuitive. Existing theory is heavily flawed as a result. These are critiques of it.
As inflation is a signal to flee money and seek (fixed) debt, deflation is a signal to seek money and flee debt. Commonly, decreasing the price increases demand, but under deflation demand for money is stronger and falling prices allow the conservation of money, so lowering the price reduces demand.
Sticky prices lead to unemployment, but they also lead to, that is, preserve, employment. The problem is flexible prices would not lead to equilibrium in general, but to instability and swings due to everyone trying to anticipate and exceed everyone else's expectations. The problem is not that they are sticky but that they are not uniformly sticky for if everything changed in the same proportion it would be as if they did not change at all. It is really that this is not true initially that creates deflation and the reestablishment of this feature that ends deflation.
As prices fall, real balances rise, but the expectation they will continue to fall induces delay to purchase, not advancement. If you were becoming wealthier at an increasing rate, you would be more inclined to delay, but while sellers may be willing or forced to sell inventory below cost, they are not likely to produce below cost, so eventually price declines reach a limit of wage declines and real balances cease to increase. The duration of the production cycle would throttle the rate of decline. At this point, there is no more incentive to delay. If prices fall, wages also fall, and attempts to save more fail as they do so. It is not rising real balances that turns deflation around but that they cease to rise, or equivalently, it is not that real wages rise but that they eventually cease to rise.
Falling prices do not lead to increased output. Flexible prices would not lead to equilibrium. Rising real balances are the result of deflation, not its end.