Hi, Sam. I own this lens and have been quite disappointed with it on my 10D and even more so full-frame. Sigma's 28~70 is much better, from what I've heard.
The 24-70 is quite large and heavy (b/c it's a 2.
but all that is wasted because it's totally unusable wider than 5.6. I've not heard of very many people happy with it. I'm looking to sell mine, if you're interested.
One thing to add...I find myself shooting (w/10D) around the 24, 50, or 70 mm marks. I probably won't replace mine with a zoom, just a 50mm prime instead. You might want to think about getting a wide-ange prime or zoom, a 50 prime, and then a 70-200f/4L (it's SHARP, SHARP).