IrishNero
Commodore
Yeah, Shatner sometimes gets singled out by fans for being difficult, perhaps unfairly, but Nimoy was known for insisting "A Vulcan wouldn't do that!"
Shatner has often earned that reputation with the fans, though that kind of reputation often takes on a life of its own and the legendary behavior becomes a round-the-clock thing in people's minds rather than the isolated events they often are. Besides, intensity, drive and focus is often mistaken for being difficult. Sometimes the actors take ownership of their characters, and want to protect them.
You have bitter, ex-co-stars to thank for establishing that. Starting on the 70s convention circuit, they (and Roddenberry) regularly peddled trash character assassination for money. You did not see Nimoy or Kelley trying to drag Shatner though the mud at every chance, but those who were ungrateful for what Shatner brought to ST, or thought (by some stretch of the imagination) that they were of equal importance to ST pushed this "bad Shatner" crap, long before any books even flirted with that idea.
Whether or not his co-stars are responsible for the whole of it, it's a classless move to perpetuate it. I think they should bury the hachet on it. It really sucks to watch a Star Trek movie with the knowledge that the co-stars actually hated their 'captain.'