C.E. Evans wrote:
The TWOK uniforms were the first Trek uniforms to have different ones for officers and enlisted and they did give Starfleet personnel a very unified look with maroon being the dominant color for everyone. The wraparound jackets were kind of stylish when they were first introduced, and they did eventually reintroduce skirts for female officers, although they did the right thing by having them be optional (IMO).
I do kind of chalk those uniforms up to representing a period of Starfleet history in which exploration did take something of a backseat to Federation defense and interstellar diplomacy. Otherwise, I always liked the TWOK uniforms, and they're only second to the First Contact uniforms for me.
One thing—to my knowledge, it was never established canonically on screen, but I always took the TOS jumpsuits as the uniforms for enlisted personnel (except when characters such as McCoy wore them in special situations such as in sickbay).
Tangential question: Was a female ever seen wearing one of those TOS jumpsuits? Uhura and Janice Lester had a sickbay nightie, but that wasn't the same.