This is an argument many use, from the casual viewer, to the non-viewer and even by some Trek fans who've never tried Trek.
They ding it over the cheap sets, the poor SFX, the papier-mache
alien costumes but most of that seems to come from casual, glancing, viewing.
Sure, you stick in an episode like, say, "Shore Leave" (an episode I love) or Arena (another great one) it came maybe come across like that.
But then you've got episodes of really great, awesome, story telling without the cheese topping (Balance of Terror, CotEoF). Watching these episodes it's almost incredible to think this sort of strory-telling came from a 60s sci-fi show and it's what stands Trek apart from shows of much greater cheese from the same era -like Lost in Space.
TOS is an awesome, great and fantastic series. Yeah, maybe to "stand" it one has to get past the production values (which for the time were first-rate but, yeah, come across "cheap" today) but that shouldn't be a problem at all.
TOS is a fantastic series and anyone not wanting to give it a chance because they saw a clip of Kirk fighting a foam-masked alien in a Bill and Ted movie is a moron.