Changing automatically transmission fluid?

I have a 97 honda civic with a 1.6L SOHC (D16Y7) and i want to know if it would be a good idea to replace the trans fluid. I bought the car with 135xxx miles and its currently at 141. The trans fluid is very dark. Nothing is wrong with the trans as far as i can tell. I want to replace it, i would be doing a drain and fill. Any thoughts on it?

A good practice with buying any older used car that you plan to keep is to change all the fluids. Then you have a baseline going forward. Engine oil, coolant, transmission fluid, brake fluid. All vital car juices.

Never flush, always drain and fill (30K mile intervals are good) and always use genuine Honda ATF DW-1. I presume you know there's no user replaceable filter.