I know I'm a measurebatur but I can't help myself.
Shot with and without IS at 4-stops below rule of thumb.
55 mm x 1.6 = 88
Rule of thumb shutter speed is 1/88 sec. each of the next four stops would be 1/44, 1/22, 1/11, 1/5.5.
These two images were shot with the Canon 18-55mm f/3.5-5.6 at f/5.6 and 1/5 sec. shutter speed.
Without IS:
With IS:



