There was always a little something "off" and unsettling when Nimoy's Spock went emotional. It reinforced that he was still an alien, and that there was a reason that Vulcan's kept their feelings bottled up. Mark Lenard (and Patrick Stewart channeling his character) also pulled this off.
This is what disappoints me with Laurence Luckinbill's performance as an "emotional Vulcan" in STV...he didn't capture any of that. Take off the ears, you're just playing a human.