The theatrical cut is missing a few great Spock scenes, but it's not a movie-breaking loss. The biggest issue really between the director's cut and the theatrical cut is the pacing. The film already looks
fantastic. The extra gloss given by the new effects is just an added bonus. The pacing of the theatrical cut is just
way more sluggish, but I suppose if you haven't accidentally broken the fast-forward button of your controller, then there's not much of a problem anyway.