This looks too heavily processed to me, which is what you will get when trying to clean up heavy noise/grain. I didnt know Nikon was so bad with noise/grain issues. What was your ISO set to? I wouldnt think you need to set it so high when shooting outside unless its getting dark and you dont want to use flash. I only have noise issues in post processing when I set ISO anywhere from 800 to 1600, but only sometimes when its set to 800.
NJ