The first thing I would like to point out is how sunny Tails still looks. There have been some assumptions that Tails doesn't take severe setbacks too well, and/or would simply become more moody as he got older. Although it was shocking to see the cyber arm and reason for the tail accessories, I'm glad to see, both in the description and the expression he is giving off in his face and body language, that he is still quite perseverant and industrious.
I also just noticed that the tip of his ears appear to be a deeper orange color. I can't I've seen this before (which was a deciding factor in giving the originality five stars), and, for some reason I can't quite put my finger on, helps bring a lot of visual balance to the picture. As for the reason for him having them, I'm guessing that they could either be scars from the accident, or (preferably), maybe something naturally occurring in which more areas of his fur will start discoloring as he gets older (I'd guess the arms, legs, and/or tails are next).
The arrangement of the scarf, belt, tails accessories, cyber arms, goggles, and feathers are arranged in a very dynamic manner. The feathers and shoulder blade on the cyber arm seemed critical in harmonizing the picture visually. The individual designs on pretty much everything Tails is wearing also work together well, add some diversity (the stripes on the shoes, the wave design on the cyber arm, the ripple design on the scarf, the rings on the around the rim of the goggles). Also, by majority, the colors don't seem to clash with each other, and mostly work well. Also, the longer legs and more hair sticking out from his head indicate him being older. It also is very nice to see that he decided to opt for the belt buckles on his shoes.
However, I do have a few comments. The first is that the cyber arm, in terms of color, may blend a bit too well with the other the other colors in the picture, and a darker color may add more contrast and impact. Also, I can't quite explain why, but, in terms of the face, Tails does not seem that much older. I can see you made a lot of effort in terms of the whiskers, ears, and hair to indicate that he is indeed older, but something still seems off in the representation. I want to say to slightly narrow the eyes (not the irises, but the actual white of the eyes), but am unsure as to how this would work in execution. However, upon taking another look at the face, I also see that you took a considerable amount of time to balance out a lot of small details (such as the slight rise in the muzzle along the bottom of the eyes), and hope that you do not take the previous comment the wrong way.
All and all, this is an original and refreshing approach to Tails that shows potential, and may require some minor tweeking.