Like others have said, deflation, like inflation, is neither good or bad in and of themselves.

Inflation favours those with debt while penalising savers.
Deflation penalises those with debt while favouring savers.
For every argument for/against deflation there's a symmetric argument against/for inflation. So it seems to me 0% is best as it favours neither.

As for the argument that deflation is bad because there is so much debt, that's just poor reasoning. What's bad is that there is so much debt.
If 0% inflation/deflation was targeted by an economy then the inevitable mild deflation would be offset by inevitable mild inflation.

Of course those who are both in debt and able to print dosh like to promote the idea that inflation is good, as it's to their benefit.

Also, the argument that people put of buying when prices are falling was once the other way round - that is it was argued that inflation put people off buying[1].

[1] http://ftalphaville.ft.com/2015/03/23/2122452/economists-agree-deflation-is-either-good-or-bad-or-irrelevant/