These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Alternate Character Interpretation: Darrin was actually very insecure and felt the need for personal accomplishments to justify himself. It is notable that on several occasions Samantha's family hatched plans to grant Darrin magical powers so that he could better fit into the world of witches. But in the end he always rejected these in order to remain "normal".
Complaining about Shows You Don't Watch: One of the biggest criticisms of the show was that Darrin should just let Samantha use her powers to benefit him instead of complaining about them. This was actually addressed many times in the show, usually with the explanation that Samantha herself wanted to live like a mortal (i.e. presents that Darrin worked hard to give her meant much more to her than something she could just poof up in an instant.) Added to that, every time Darrin tried to accept Samantha's powers, it usually would cause chaos (i.e. it would go to his head or someone would find out and blackmail Sam), so he actually was somewhat justified in not allowing her to use her magic.
There is also the issue of Sam being forced to be a housewife. Darrin was perfectly willing to help Sam with the housework, and this can be seen in multiple episodes. He just did not like her using magic. That said, Samantha came from a background where she did not have to do housework at all. There is a certain social class subtext here. It is like a very wealthy heiress marrying a middle class man. In fact, one wonders whether the rich ex-girlfriend that Darrin had would have consented to such a middle class lifestyle, or if she would have insisted on using her family money to fund something more lavish and how Darren would have dealt with that. It might have been the reason he did not marry her.
One early episode had an Imagine Spot in which Darrin imagines his future children with Sam, including a witch-daughter named Little Endora. If you consider "Passions" canon to the series, Sam and Darrin would later get a granddaughter named Endora.
Hypocrite: Darren. He strenuously objects to Samantha using witchcraft for anything, even just to make her domestic life easier. Yet he readily uses modern technological conveniences and even has a secretary!
Most Annoying Sound: Alice Pearce would sometimes use an excruciatingly screechy voice as Gladys Kravitz. Highlighted in one of Nick At Nite's ads for the show when they started airing the old black-and-white episodes.
Recycled Script: By the end of its run, the show was recycling its own scripts.
Seasonal Rot: The Dick Sargent episodes in particular are victims of this.
They Changed It, Now It Sucks: The "Tabitha" spin-off, among other things, retconning Adam to be a mortal (as well as Tabitha now being the younger sibling) despite the pilot showing him to be a warlock. Apparently, the original audience was also upset that Tabitha and Adam were suddenly adults.
Values Dissonance: Darrin's behavior seems remarkably jerkass and repressive to modern sensibilities. Depending on whom you ask, this was stepped up when Dick Sargent came on as Darrin.
In particular he seemed very hostile to the idea of Samantha acquiring a "career" as Queen of the Witches and states it in pretty much those terms, actually denouncing her comparison to the U.S. presidency on the grounds that no president has ever been a wife and mother.