In a simple way, "Westworld" is like watching Jurassic park movies but instead of dinos, it's terminator robots with "Memento" and "Inception" type story complexity. Well, I'm not trying to explain that it is a copy of this and that... It's a totally new and amazing story.
Seasons 1 & 2 are way crazier or more than amazing. It just consumes your mind, I mean it's engaging. Storytelling is like you have to solve the puzzle of what's happening in the story to understand the meaning behind it, and hell yeah it has deep meanings related to human vs AI and the concept of the fittest one survives, etc etc.
The problem was season 3, literally, it was not that interesting... I mean it didn't have the taste of the theme like the previous season. Maybe because they were trying to introduce another side of the world, which really didn't work. But yeah, season 3 is also important to understand the depth and story given to our favorite-main characters and also very important for the twist of season 4's first half. So you can't skip season 3 if you really want to experience season 4 very well.
And coming to Season 4, my favorite part was the horror elements added in the first 2-3 episodes of this season... It was like I'm watching sci-fi but also sometimes it's scary/dark. (Which builds interest in my mind to watch robot movies like terminator in horror theme). Also, the twists and story of season 4 brings back the taste of season 1 & 2 (which makes it more interesting, just like the early seasons). Season 4 is just a flip with its own complex story. For which season 5 is a must.
Unfortunately, HBO has canceled the final season 5, maybe because of WB & Discovery merger. But you can't leave a story open... It needs to be closed... It needs an ending.. a beautiful ending with a beautiful character arc for our last character. Right now it's up to fans' imagination which was built with the great journey of 4 seasons.
If you are a big fan or interested in storytelling techniques like Christopher Nolan use in his films (obviously one of the makers of Westworld is Jonathan Nolan who is a brother of Christopher.. aka Jonathan helped Christopher in writing stories like Memento, dark knight trilogy and he wrote the story for Interstellar, so you can imagine the potential) then Westworld is something you should watch.