CAN be great: Excample like Diablo comes to mind.
CAN be horrible: Persona 4 dungeons lol (persona 5 has hand made dungeons, yay)

anyway it really depends on the game, but making a game around it is something no man in our sky should want XD

It's very hard to pull off right, but I believe that guided level generation can be great for extending replay value.

Case by case basis and how well the dev can implement it.

In the division, one of the DLC updates had something called the Underground. Randomly generated maps reusing the same assets over and over and over and to often times poor effect. The way they did it kind of sucked.

Enter the Gungeon - randomly generated mostly, but includes important rooms incorporated into each level. It actually adds to the replayability due to the sheer variety of weapons and encounters, but also because it's a shorter indie game and there would be little point playing again after the first run. As it is, Enter the gungeon is fantastic and each run allows you to get a little bit better while adding enough variety to keep you on your toes. I really like this game and how everything Is put together.

Sometimes it can be lazy, other times it can be key to replayability/exploration etc. Just depends on the devs/genre/game

It's nice and adds in a level of randomness to gameplay, but usually feels pretty gimmicky. If it's a side/extra like grottos in Dragon Quest IX or the Sharance Maze in Rune Factory 4, then I'm fine with it

i don't know, depends on how well it's implemented

I like them, and can be very exciting if done right. Games like Minecraft and Starbound have enough variety and goodies to find that it makes restarting a game all the more exciting, because you never know what going to happen, or what you're going to find next play through. I've only played a few of this type of game, so I haven't grown tired of them, nor dislike.

One of the few games with random level generation that I've played is Dark Cloud 2 and my least favorite part of that game were the randomly generated dungeons. To me it was a chore to get through those dungeons, especially later in the game, when they started to get really long.

I love it in Minecraft, The Binding of Isaac, Darkest Dungeon and Don't Starve.
But it has to resonate with the kind of game it is. TloU for example would be horrible with rng because everything is crafted towards the narrative experience in that game and the level design tells half the story. Rng would simply not work with that.
So it can be an excellent tool if used correctly.

I hate randomly generated stuff. If something can be randomized, it cannot be very important or unique to the game world. It's just fluff. It cannot be as detailed as something that is designed to be unique. I also don't see the replay value. It's not new every time, it's just the same components rearranged in a different order. Can't fool me. Boring.

It's a great tool for certain types of games but they require sophisticated generators or the levels will come of as bland and boring.