The condition portrayed in the movie is a real one and a rare one - BIID - Body Integrity Identity Disorder - a disorder in which otherwise healthy individuals feel that they are meant to be disabled, each in a very specific way.
The main character's difficulties in dealing with this deep desire and disclosing this to his wife are difficulties that real people with BIID also face. I haven't seen many movies with a BIID theme, but compared to "Quid Pro Quo" which may be a more entertaining movie, this movie is more true to the reality of BIID.
For me it was definitely a drama, not a comedy - that's not to say there is no humor. Feeling that the true you is arm-less and not achieving this arm-less state means continuing to live a lie and trying to work through this without devastating those close to you is the stuff of drama, not comedy.
Despite the good acting and important content, I can see how this is not a movie for everyone. If you have an interest in BIID, I would definitely recommend it.