Shade so far has presented himself only in his human form. However, with the exception of grey coloration and slightly alternative style of clothing, he looks identical to Shadow. A distinguishing characteristic though is that Shade has clearly defined orange-on-black human eyes (with Shadow, it is red instead of orange).
Unlike Shadow, Shade seems to have more of an aggressive streak. He will attack at his own will if he chooses to, and can be extremely flashy when he does, though he is still subject to Ignatio's will. Like his master, he is often smiling, but generally this is never with friendly intent and likely a streak of arrogance.
Shade is capable of teleportation and can directly attack his opponents like most other yongmas. The full extent of his abilities and weaknesses has yet to be seen but most likely they are identical, or nearly identical to Shadow's.