well - I suppose that a lens like this is always going to be a little bit of a "marmite" effect. Personally, it's just too much, but of the three shots you've posted up, I think that it suits the first and third subject matter better.
The first one really shows the chromatic aberation on the outer edges of the shot, but with such an extreme lens, It's unsurprising. I do like the subject, and the colours work well. It also appears a touch sharper than the others - though this may well be partly due to the small image sizes posted.
Second shot is just a little "too busy" for me - just too many twigs and branches to get my head around and to un-pick the lens distortion from.
Third one is probably the best subject matter to illustrate the effect of the three chosen, though I'd have been inclined to have had the thickest tree-trunk at the bottom of frame rather than the top - as it is, it kind of breaks the area where you "expect" to see the sky - the upper half of the frame - in two, and draws your eye into the darkness. At the bottom of frame, it'd "point up" into the shot... and yes - i did stand in front of my monitor, with my head inverted, looking at the screen to work this out