Ketil, I like the photo, but might have liked it better had there been better color? For the photo you have, I think the cropping is good (I like the small tree limb). But most of all, I like how you handled the DOF - canon's 100mm macro does a great job with this!
I love these kind of minimalistic photo's but an other, more colorfull leaf would have been better. For my feeling the branch also disturbes somewhat so qua composition it could be go in the right-up corner, pointing into the photo.