I continue to wrestle with open worlds in general - I feel like I hold them to a standard that almost no games actually meet, but I
do
often still enjoy the ones that fail to meet that standard. It just feels like they can and should be so much more, you know? I feel like "open world" games fall into one of three categories pretty reliably:
The actual immersive world
- Feels truly lived in with recognizable significance, relationships, consistency and maybe even politics between both yourself and all of its residents. The world is dripping with things to do, actually interesting characters to interact with, quests to undertake and meaningful rewards (read: wholly unique rewards if not completely new branching stories) for exploration. (I honestly haven't played a single game that feels like it meets this standard outside of New Vegas, which I hold as the one truly good open world game. I'll note that a big miss of mine is having not yet played The Witcher 3, so maybe there's hope!)
The grand tour
- The world has a very clearly thought out structure and may even be breathtakingly beautiful, but is obviously designed to just lead the player through and marvel at stuff with little if any focus on making you feel like you actually belong and have a real connection with it. Rewards for exploration are typically meager, self-created or copy/pasted. In some more extreme cases, going out and exploring actually has very little purpose if a side quest isn't pointing you to that particular nook or cranny. This is the open world equivalent of being on vacation, IMO, you're just seeing a ton of cool stuff and moving on without a second though, as foolmo said. (Your BotWs, FFXVs, Xenoblades, Assassin's Creeds, Bethesda FO/Elder Scrolls and such of the world go here)
The sandbox
- Not really a true structured "world" so much as it is a big ol' map that can accommodate everything that's going to happen in the game. Exploration is de-emphasized to the most it can be, and the open nature of the game exists basically purely for the sake of immersion and being seamless. The most fun you can have in these games between missions and mini games is usually just causing chaos and messing around. (Your GTAs, InFamous games, Just Causes and weird cases like LA Noire all go here)
Let the voice of love take you higher,
With this gathering power, go beyond even time!