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.
Broken Base - The issue of whether the later series are as good as the older series, for starters.
Fridge Brilliance: Since Skull was chronologically the first Rider to appear in the Double-verse, it could be argued that the Spider and Bat Dopants actually were the first MotWs in Double.
Macekre - "Saban's Masked Rider". To capitalize on the success of Power Rangers, Saban licensed the already Lighter and SofterKamen Rider Black RX, dialed the Lighter and Softer elements Up to Eleven, and turned it into "Saban's Masked Rider": a lame old Aesop-tastic romp of a sit-com starring a superhero alienlearning about Earth culture with his adoptive American Family. Later the editing got so shoddy that at times you could clearly see the original Japanese actors, or the fact that the footage they were splicing in was from a completely different series starring a completely different hero. (Dex is Black RX one scene, J the next! No, they don't look alike. At all.) To say that Ishinomori was disgusted would be putting it too lightly. Not to mention that the events of the series have been Retconned to be a Show Within a Show in Power Rangers.
Most Wonderful Sound - For anyone surrounded by monsters or whose town/world is being threatened, when all hope for survival seems lost, one word can banish the darkness and bring salvation. That word? HENSHIN!
Paranoia Fuel - Ryuki. Just think about it. Every mirror - hell - every single reflective body you walk past could be a portal from which a monster whose only desire is to eat you could emerge from. And don't think it's just that odd piece of glass in the streets, or that puddle of water you need to worry about either. Every mirror is fair game, even the ones in your home. Really, the only guarantee of survival in the Ryuki world possible if you were just a 'normal' is to lock yourself in at home and cover up every piece of glass.
...Or if you somehow found a discarded deck like Shinji did.
Let's keep going. The monsters are essentially relentless, and will never stop hunting you once you are chosen as a target. Lousy luck if you're in the dark about, but if you are aware of their existence..... This applies to Dragon Knight as well, with the trade off of mindless monsters that will eat you at the first opportunity for an organized force that is just waiting for it's shot at conquering the whole damn world, and if not for the Riders, would have succeeded.
We should also count the series where the monsters can take human form. like the worms of Kamen Rider Kabuto. They kill the original, and take that person's place. An impersonation so good, that they can fool anyone, including THEMSELVES! This means that anyone you know, Father, Mother, Best friend, ANYONE could be a worm in disguise. Lovely thought.
What about the organization that started it all? Shocker is everywhere. If you are in their sights, whether it be a random target or worse, if you're a witness, they will find you. Your home is no longer safe, your friends might be monsters in disguise or already dead, your drinks might even be poisoned—No matter what you do, they will always be five steps ahead. Sure, Kamen Rider 1 or 2 can save the day, but lord forbid you're the first victim of the episode. You know, the one nobody ever saves...
Unfortunate Implications - Female Riders are few and tend not to end well for the most part, starting with the death of Tackle of Stronger (who, to add insult to injury, was later officially ruled to not be a true Rider, only a mere sidekick to Stronger). There are also isolated cases of brief sequences of women borrowing male Riders' gear and ending okay, but that's not the same. Kamen Rider Decade is showing a good track record with female Riders, though: several past ones return, are handled with much more respect, and survive, and Natsumi gets a suit and survives (albeit in the finale movie only.) It's joked that the time Apollo Geist sucked out her life force (she got better) counted as the mandatory death, and with it out of the way, Natsumi is exempt. However, it is somewhat mitigated by the fact that a great deal of male Riders do not survive either.