[dutchflyboy]

Well, in the worst case, you just re-apply the filter on the part you're not satisfied with (for example, those white areas at the bottom).

[drats]

It is a great starting point to make Trotsky-duck disappear on Stalin's orders. http://i.imgur.com/xK6Jl.jpg The wealth of free tools is just amazing these days.

[thingie]

Well, it's still quite obvious that something is missing there, as the central area of the picture is visibly less blurred than its surrounding. I guess you could fix that easily by just blurring it with ordinary gimp blur. (But great start indeed, comrade. :o))

[cma]

Another technique is to normal-crop out the sky and the distant grass that is so blurry, "content-aware" crop out the duck, then paste back in the stuff you originally cropped out. The white bits at the bottom are sky. The blurry bits are where grass far in the background was stitched in.