Not a bad idea, take old dresser drawers and put them under your bed for storage

A few things I would do differently.  I would add casters to the drawers so the slide out easier.  And if I was going to paint the drawers I think I would move the handles so they match the other drawers in high.

http://www.ikeahackers.net/2015/03/dresser-bed-drawers.html