Edward, Congrats on the new lens! Looks nice and sharp -great details. If you had rotated the image a bit I wonder if you could have eliminated the OOF leaf at the bottom left,or made it smaller. Or crop a bit off the bottom. Nicely done!!
The sharpness and colors are outstanding, Edward. I also like the comp and the fact that the fly is facing just slightly towards you. You might consider toning down the OOF light areas in the LLC. Well done.
I agree with all the other comments - that is one 'in focus' fly! The only thing I can see that nobody else has mentioned are the white spots on the fly's body...if they are pollen then I'd leave them...if they aren't, I'd consider cloning them out.
Congrats on the new lens! I just got a new-to-me 400mm this week so I know what fun a new lens is!