I love the original episode, but the poor special effects (especially the close-up of the Constellation entering the Planet Killer near the ending) take me out of the story. I feel the re-mastering is an improvement and only serves to assist the character-driven storyline.
To me it is quite the opposite. The shiny new 21st century CGI effects clash so much with everything around them that it yanks me right out of the story because it is so jarring.
But honestly, if people get pulled out of stories by shoddy FX, then perhaps they shouldn't be watching 40 year old low budget SciFi TV shows.
And a true "remastering"--which I would have welcomed-- wouldn't have added any new elements to the episodes, merely enhanced what was already there.
"Canon is only important to certain people because they have to cling to their knowledge of the minutiae. Open your mind! Be a Star Trek fan and open your mind and say, 'Where does Star Trek want to take me now'." - Leonard Nimoy