77mm filter; 670g; 3 stops IS; a great travel lens; RRP $A2000
similar image quality to the 24-70L but lighter, more range and IS thus better for stationery subjects whereas the f/2.8 on the 24-70mm means its better for moving subjects.
CA at wide angle f/4; not weather resistant; some vignetting on 5D at < 50mm focal length; more distortion than the 24-70mm.