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.
Frank is usually treated as a absolute moralist who just happens to be fighting a never ending war on crime. Other interpretations imply he's just as bad as the monsters he fights and is little different from a serial killer. The only thing that stays the same is the reason why he became the Punisher.
Punisher: Year One has yet another take on Frank's character - he goes vigilante only after all other methods of bringing the mobsters who killed his family to justice fail spectacularly (the police is ineffective and corrupt; an attempt to do an independent investigation leads only to death of the reporter whom Frank briefly befriended).
Punisher: Born from MAX imprint has a different take on WHY he became the Punisher. Frank fell in love with killing and made a deal with an unknown supernatural entity (or just plainly went mad, you choose) to fight a war that would last forever. He wasn't informed until later that the price would be his family, at which point the supernatural entity makes Frank forget that they ever made the deal.
For instance, in an early appearance, he tried to kill people for running stop signs and littering (this was Hand Waved in The Punisher: Circle of Blood by saying he had been drugged by Jigsaw to make him more violent and hardline).
Sequel Displacement: While Frank was one of Marvel's cash cows back in the early nineties (alongside Spider-Man and Wolverine), many of his modern fans know nothing about his stories before Ennis. Sadly this means that a lot of his gentler characterizations are overlooked, as well as the fact that he actually did have something of a supporting cast.
Which is what a lot of fans said of Angelic Punisher.
Many people feared the worst at the announcement of Franken-Castle. Surprisingly, the change has been immensely popular. So much so that his ongoing series was renamed Franken-Castle for a little while.
Writer on Board: Garth Ennis hates conventional superheroes. You cannot help but notice that whenever any of them appears in an issue of the main Punisher series written by him.