I have to admit as a kid I found the original E to be a bit clunky and outdated, but that was probably mostly because the low-grade effects never really did it justice.
But eventually I came to appreciate the design a lot more-- especially when considering just how different it was from what came before. Because I'm pretty sure this is the first time we saw a spaceship on screen that wasn't
either a flying saucer or a rocket ship.
It's amazing that it took until the mid-60s before someone realized there were lots of other possibilities out there for spaceship design.
And of course the Enterprise sets
are incredible as well. Especially compared to the rather generic scifi designs still being used on Lost in Space at the time. The TOS sets might look a bit outdated and 1960s now, but at least they had a real and distinctive style