Just watched this. Stylistically, I enjoy this episode from late in the run thanks to its espionage plot and the presence of two-time Bond girl Maud Adams to elevate it. I'm also intrigued how elements of it freely borrow from the 1956 novel "Forbidden Area" by Pat Frank which was adapted into the first ever episode of "Playhouse 90" (teleplay by Rod Serling) and starred Charlton Heston, Vincent Price and Tab Hunter. That story was about a Russian spy (Hunter) infiltrated into the US on a beach (just like the doppelganger in "Deep Cover") with a "Deep Cover" identity to infiltrate the US military (though for higher stakes). The critical plot point of "Deep Cover" about stainless steel fillings leading to the murder of a dentist also comes out of "Forbidden Area" where Hunter does in the too-talkative, too-inquisitive dentist (Jackie Coogan).

But I do agree with Mike that the episode itself has a number of problems structurally and that parts of it don't hold up well compared to other great "espionage" episodes of the series.