I really love the composition of the piece. The white of the face, hands, cane, collar and cuffs really help to direct my eyes through the piece. I think the black trim at the top and the bottom also assist in unifying the piece. Since the black hair and eyes are so striking, the black trim gives a strong block of value to balance them out. The shading is used to define form and it doesn't get overly detailed, which I believe accentuates the focal point, the face, as well as the gesture of the hands. If there is one think I'd suggest for improvement, I would encourage just a little bit more shading on the hand holding the cane. As it is, it looks a little flat in comparison to the rest of the picture.
Generally I love your art, but I think this one missed the spot. It looks very flat, and while I assume it was intentional, I think it needs to be either slightly darker (in the shadows) or less flat overall. The clothes are excellent; it's really just the shading on the skin that needs improvement. His hair also would benefit from looking less homogenous and generically 'flat and mildly shiny'.
Next, the proportions in the face feel very 'off' to me. Wilde had a long face, to be sure, but this doesn't look exaggerated so much as wrong. I'd say his eyes are too high, and the edges of his face are not parallel enough (too curvy/wide near his cheekbones, particularly on the left side). Work on keeping his face shape a little more symmetrical, and play around with the eye placement a bit.