IMHO, the original Enterprise bridge is still one of the most practical, functional and believable sets ever created for a sci-fi film or TV production.
Much as I love the bridge as a visual experience, it has some problems.
- To get from the captain's chair to the elevator, Kirk had to take two steps down, turn 180 degrees, and then take two steps right back up again, and squeeze between the chair and the red railing. (The gap varies between episodes as the captain's chair was moved forward or back to accomodate a scene.) Or he could go the long way to the port-side bridge steps and double back for the whole distance to the elevator.
- The red railing makes some sense if you are down in the well, but for people up in the outer ring, the railing is at just the right height to bust both your kneecaps as you fall over it and face-plant in the well during a battle.
- Spock's hooded viewer would be a nightmare to have to bend over and use for any length of time. Back ache! Needless to say, it was a concession to the budgetary problem of creating data displays with the actual info (as was done in "The Cage" with now-dated effect-- Lyndon Johnson, anyone?).
- The buttons on each outer-ring station, e.g., Uhura's panels, are arranged in an arc that is exactly the opposite of what an ergonomic keyboard does to reduce stress on the wrists.
- It famously lacked an emergency exit, but Franz Joseph showed how easy it would be to have a wall panel that opens so I don't consider that a big design issue.
Still, for all that, it's awesome and I love it.