I also didn't buy Sybok as Spock's half brother. Just felt tacked on.
Would have been better if he'd been a Vulcan Spock was close to as they grew up, a maverick who treated Spock decently when they were younger, hung with the half human that the other kids didn't want anything to do with. But later, those same maverick impulses, once they began down a certain path, would see them part ways.
THAT would have been better. Would have taken a bit more explanation, but would have been more believable to fans.
The Old Mixer wrote:
-Laurence Luckinbill's performance
If he'd been playing a human character, I might agree. As it was, Sybok was very poorly realized. An "emotional Vulcan" could have been portrayed as somebody who was Vulcan first, and emtional second. As it was, he came off more as a rather gregarious human who just happened to have pointy ears. There was nothing Vulcan about him beyond the superficial.
He even contradicted what we were always told about Vulcans--that they learned to suppress their emotions because they were such a violent people. An emotional Vulcan should be more of a scary bastard.