While technically sleeping advances time, there are actually very few situations where a long rest actually impacts any of the storylines. It may be poor roleplaying (or maybe not.. if I almost get my ass beat killing a pack of Gnolls, I'd probably call it a day), but I pretty frequently long rest after every fight. This is (fortunately, IMO) not one of those games where if you wait too long, quests expire. The only exceptions are a few cases where you'll complete a major portion of the game, and a long-rest will trigger some of the quest-related NPCs to effectively move on to the next act.

There are also rest-related events that happen that, as far as I can tell, are more or less independent of the main storyline. It might be that they're related to discovering a certain area or advancing a quest to a certain point. If you don't long rest enough, you run the risk of missing some of this content.

So based on my playing experience, it's better to long rest too much than not enough. My only beef with it is that it takes a long time - you've gotta re-zone into your camp, play that stupid food minigame, talk to anyone who needs to talk to you, watch that stupid sleeping cutsene, then re-zone back to the game. I get why they did it (there's a chance at any rest that you won't sleep peacefully), but I quite like the D:OS bedroll mechanic, where you just click the thing and you're instantly rested and you keep going... much like a short rest. But that's just me.

I will agree that the whole spell slot thing confused the hell out of me, too, since so many games use spell costs and a mana pool. This is a mechanic that makes tabletop quite a bit easier to play and enforces some balance... but I agree that's very different from many video games you'll play.

You're right about the learning curve. The character creation system itself became quite a bit less intuitive in the full release as well, IMO. Fortunately, the ruleset is pretty forgiving, so you can make any race function well as any class. Once you encounter Withers, you can also re-class yourself for a small fee (I think like 100g... it might go up with subsequent reclasses, I don't remember). That's a lot early in the game, but midway through you won't think twice about 100g.

Finally, casters really kinda suck at early levels. Like, REALLY suck. They're squishy, you don't have gear to compensate for their squishiness, their cantrips barely do any damage, and their spells are barely better than their cantrips. Late game, however, they're pretty powerful... you just have to put in the time to get there. There is a ton you can discover about the world. Like in many other games, you discover books throughout that usually serve very little purpose other than to explain the world and the backstory. You just need to spend some time exploring bookshelves to find them.

This game (and D&D in general) is all about telling a story. If you're creating your own character, it's up to you to make up their backstory. Many people would feel it quite limiting to have a backstory thrust upon them (like in D:OS or DA:O). You pick noble as their trait, but you need to decide are they a greedy, selfish mercenary type? A benevolent, generous benefactor who wants to better the world? Some mix in between... you're creating the character, so it's on you to create their backstory and play them according to the backstory you created.

As for the characters, they're **WAY** more complex than they first appear. You just need to play long enough to develop their story. I don't come from a D&D background either. You pretty quickly get the sens that illithids are bad news, but not much else right away. The game does do a pretty good job explaining where they come from, what their mechanics are, what their culture (if you want to call it that) is, etc. Again, it's part of the story that unfolds as you play. There are very few situations where a single dice roll can block out significant content. If you have karmic dice enabled, this gets even smaller. Add to that the fact that you can hold up to 4 inspiration points at any time, and there are *TONS* of inspiration point opportunities, and you get lots of chances to re-roll some of those critical things.

If you fail a roll and don't reroll, it does take away certain options. There was one point where I was super annoyed at that I couldn't pass a certain roll, but I rerolled that thing 3 times and failed. I just didn't have enough wisdom or whatever the stat was. It happens, that's part of the game. The challenge in the game is finding an alternative way to go when that happens.
The one spot where you might get locked out of content in a playthrough is when two recruited characters don't get along. If you fail a roll there, you may be unable to convince them to make peace, and have to choose one. You can only ever have 4 characters in your party at a time anyway, so you'd spend a lot of time trying to predict who needs to be with you in a given area to get the in-person interactions you want... ultimately, I found there really wasn't a way to experience all the content in a single playthrough regardless of those rolls (on my first playthrough, I passed all of them anyway. I failed one of them on my second...). If you miss out on some content one time, just go after it on a second. pretty bold move of you to base your opinion completely on someone else's review of the game. I *have* experienced the end of act 3, and although I would definitely love to have had more areas to explore, I don't get the impression that things were cut or missing, or that the story had holes. I also didn't encounter many bugs. There were a few small things, like a random dialogue that triggered that wasn't related to anything I was doing at the time, but in all my lived experience does not reflect the way you phrase it. Who is 'you' here? Larian? If you want them to read it, go post on the Larian forums.
Literally anyone who gets that message will, by definition, be reading it. What do you expect to achieve by posting this here?

If you don't want to play anymore, that's up to you... but it sounds to me like you didn't really give it a chance before letting someone else make up your mind for you. That's one way to live your life, I guess... but it's not how I'd do it.