It's hard to compare any lens really to F because it's an 11x zoom. But here I pit it against the E (3x zoom). Since they both offer stabilization with similar fstops from 18-55mm, and since many will ask which is the better walkaround, here are my findings and comments.
In favor of E (1855 IS) is its lower price tag, it's significantly lighter weight and smaller size, it's dead-quiet IS mechanism (you can't hear a thing so at first you think it's broken), and it's slightly better edge performance. A nice walkaround lens at a low price that gives you a good wide angle on APS-C with IS.
In favor of F (18200 OS) is its significantly better build quality (including metal rear mount), its massive 11x range (versus only 3x of E), faster at 55mm (f5 wide open versus f5.6 for E), non-rotating frontal (for CP filter ease of use), and optically, F is better in almost every facet (see UPDATE section below). Its center sharpness at every corresponding FL is better, it delivers better contrast at every FL (wide open), and has better flare, bokeh, and CA performance. Distortions and shading are similar --- both slightly below average. F really is a very good lens that gets a prima facie bad rap if only for the bias against superzooms. I actually will recommend both, but I do recommend F much more if money is not an issue. [NOTE: I have only used 1 copy of E, so I am more than willing to be open to the fact that my particular E copy is a bad or poor copy. I just don't know. AF accuracy seemed fine in every respect, however.]
Update: When looking at "E v F I" on this page, the difference between the two lenses is significant at the 55mm mark. In this particular comparison, E is at its longest FL of 55mm and wide open at f5.6; F is set to 55mm and stopped 1/3 down to f5.6 (wide open for F at 55mm is f5). And as you can see, there is no comparison. And this caused me to wonder how E could be so "poor" in performance. My standard procedure was implemented during testing: tripod, static subject, wired shutter, fired off 6 frames (forcing refocus after each frame), and everything was done identically for both lenses. Then in photoshop the best capture is used and posted here. Yet the difference at 55mm is so great between the two lenses. If you look at the main test page and see the "50mm" tests, you'll see that the difference there is not as great (though in that test the lighting was outdoors which generated significantly higher shutter speeds with no low light potential issues), even though F still is the better optic. My thinking was that there must be a drastic difference between E at 50mm and its longest FL of 55mm. So I decided to run another "controlled" test with a different subject, but with lower available lighting conditions. This time I fired off 9 frames for each lens at each setting, then chose the best. As you can see in "E v F II", E is tested at 50mm f5.6, then 55mm f5.6, and F is shown at 55mm f5.6. The result? Yes, E does resolve slightly more detail at 50mm than 55mm, but still, F is clearly the more crisp, sharper, and more contrasty lens. So the summary is that while E is definitely an improvement over its non-IS predecessor, it cannot best the 11x superzoom from Sigma. As shown throughout this comparison, be it flare, CA, bokeh, sharpness, contrast, no matter the FL from 18-55mm, F wins out and often convincingly. For me, having used these lenses and viewed countless images from both, the matter is settled --- E is a nice, new lens at a very attractive price, but F is truly a phenomenal superzoom. For the "icing on the cake", see the "Range" page.