To my understanding, the goal was to simulate what might have been done in the 19609s had the budget existed. So warp takeoffs, etc, would look the same.
Where the new f/x really come in handy is with minor details- Khan's ship being discarded, asteroids bouncing off the hulk of the USS Constellation, seeing more Romulan and Klingon ships together in "The Enterprise Incident", space hippies getting a properly shaped ship, where Klingons had ships other than a red spinning wheel missing only a backing soundtrack from Blood Sweat & Tears, more graceful shuttlecraft with unique identifiers like the one in "Let That be Your Last Battlefield" or "Journey to Babel", and so on...
TBH, TOS-R had some very thoughtful recreations with detail to overcome the limitations of the rendering, which looked a little dated given the time it was rendered - too flat, limited contrast, etc... The CGI needn't be photorealistic to do the basic job right and in some cases it almost looks photorealistic... I'll agree it could have been better, more time to do the rendering, added polygon count, etc, etc... but where they paid the most attention to, it more than makes up for any nitpicks.
But I will say this - to this day, whenever I rewatch "The Immunity Syndrome", I only watch with the original effects regardless of how well they did the space amoeba and inside-the-protoplasm-goo scenes. The original f/x just feel more ominous despite the improved lighting f/x.
