If you can avoid shooting wide-open, and preferably stay somewhere near the middle of the zoom range - oh, say about 20mm to 45mm, the kit lens does just fine. (As you know.)
I swapped mine for a 24-105 a little while ago, and I'm not actually all that happy about it. The new lens, while a wonderful bit of kit, is heavier, larger, and most of all doesn't give me 18mm wide angle. So, assuming I can find a buyer for the 24-105, it's back to the 18-55 for me until I decide what to replace it with.