I don't see him as a primma donna.
The holdout is because Subban wants a second contract along the line Seguin, Skinner (who singlehandedly ruined these contracts), Benn, Hall and Eberle all received.
Whereas the Montreal GM wants to give him a "bridge" contract, where Subban plays for 2 years on a cheap contract to prove his worth before getting a payday. Pacioretty and Price both received similar deals from Montreal.
Montreal has offered a 2 year 5 million (2.5 per year!) deal to Subban. From Subban's point of view, Montreal is asking him to surrender two years of his big payday for the sake of the team. From Montreal's point of view, Subban has not earned a big contract yet.
Subban isn't being a primma donna. He isn't where Pacioretty and Price where at his stage. They were players who had shown flashes of the hockey elite while at the same time shown inconsistency in their play. They weren't elite yet.
Subban, while not "elite", is certainly more established then they were and more worthy of a contract closer to the longer term second contracts we are seeing. He has been Montreal's consummate defender in all situations for the past 2 years. He's out there for the important PK and for the 6th man rush at the 30 second mark. He is much more valuable.
Montreal is just being stubborn for the sake of semantics, and they may lose the best defenseman they have had in forever (who isn't hurt 98% of the time) because of it.
From what I have read, Montreal will match any offersheet save for the ludicrous. They don't care as long as they didn't sign it. Montreal will match that offer sheet in a second.