Is Malvolio sympathetic or unsympathetic?

Malvolio from Shakespeare's Twelfth Night begins the play as an unsympathetic character, but I would argue that he becomes sympathetic over the course of the comedy due to the horrible mistreatment he receives at the hands of Sir Toby, Sir Andrew, Maria, and Feste.
Malvolio is one of Olivia's servants, though he has a comically high regard for himself and thinks himself above his station. Pomposity is his defining character trait, a fact for which the play ruthlessly mocks him. His self-involvement is meant to be seen as ridiculous.
Sir Toby and Maria, with some help from Sir Andrew and Feste, conspire to knock him down a peg by playing a cruel prank. First, they make him believe that Olivia is in love with him and trick him into dressing in an outlandish outfit. Olivia, not knowing why he is behaving so strangely, thinks he must be mad. Toby and Maria then confine him in a dark room and treat him as a madman, calling in Feste to pretend to be a doctor. In modern parlance, we might call this gaslighting. They conspire to convince Malvolio that he truly has lost his mind.
It is up to the reader or audience member to decide whether this punishment fits the crime of Malvolio's ambition. Does he become a pitiful figure and thus transition from unsympathetic to sympathetic? I think yes, but another interpreter might say he got exactly what he deserved.