Bitcoin and Deflation - A Real Concern?

I saw this post on r/cc today, and was interested in some input from people here.

The argument that deflation can hurt the economy via lower levels of investment, production, hiring, etc. is pretty compelling, and likely one of the strongest arguments against the adoption of a deflationary currency. But it still doesn't seem right, despite my not being able to put a finger on exactly why I feel that way.

Thoughts?