TLDR version: This game is an enjoyable experience in its own right, but somewhat disappoints because it had the potential to be so much more, but apparently not the budget or development time to fully realize those ambitions.
Actually, despite my bitter disapproval of very specific elements of the game (no 2011 game should "lock you out" of 95% of the game once you pass a certain point), there is actually much to appreciate about DS3.
I think many people, myself included, were most disappointed because there are many things that are done very well, but it feels like they were not developed to their full potential. The graphics are charming enough for this type of game, so I have no issues there, although a little more variation when it comes to the armor sets would have been appreciated. The combat is, in my opinion, the best thing about this game. I understand why some gamers consider it a bit on the shallow side, because it's fairly simplistic, but I think it's a good thing in this instance. It's not contrived, and very organic. Once you get used to the controls, you can seamlessly switch stances and weapons, and I know MANY people would disagree with me, but I find combat in DS3 superior to combat in juggernauts like Diablo 2. Don't misunderstand, there's some room for improvement, but being able to actively dodge around like an action game is FAR superior to relying on the traditional RPG approach of having a character essentially remain stationary while hacking at enemies which in turn hack at them.
If the combat is the best element of the game, then the multiplayer is arguably the worst. It's not that it doesn't work, it's just a tad underwhelming for this age of gaming. The camera is rather wonky, and forces all of the players cameras to conform to the first player's camera. This, combined with the camera being zoomed in too closely, means you can't see what the heck is going on half the time. The beast fight in particular was incredibly frustrating. How can I dodge away from a rampaging behemoth if I can't even see it until it's right on top of me? Also, the "pro bono" take on multiplayer is a real bummer, as you can't take away items or experience if you participate in another person's game. To give credit where it's due, a real gem in DS3 is how the computer AI will take over for another player if they've been afk for a minute or so. This allows you to keep playing if a companion has to drop out for an hour to go grocery shopping or the like.
Something that most players admit lacked depth was the loot system. This is a major problem as dungeon crawlers thrive or die based on the sense of reward instilled by the looting system. DS3 is an odd duck here. It's not that it lacks variety, per se. On paper, there are enough stats to keep things interesting, with poison, retribution, doom, etc. The problem is, none of it really seems to matter all that much. You have roughly the same experience going through the game with common gear as you do with endgame rares. In that sense, the loot system feels hollow. Also, some of the "best" gear in the game is purchased from vendors, as static spawns, no less. That sort of defeats the philosophy of exploration and hunting that's supposed to define games like this.
The story is actually quite good, but I think people fail to see that because the way it's presented comes across as rather flat at times. The couple of voice acted sequences are somewhat unconvincing, and the bulk of the story, which is pretty detailed, comes via texts that the player discovers around the world, but I doubt that many people spent much time reading them (I did, and somewhat enjoyed them, but only after I finished the game, I found that reading them as I went broke up the action too much).
I think, all of this aside, that this game is still a good deal of fun, and players would have overlooked many of the shortcomings if not for the fact that the game is so short. I'll be the first to say that I'll take a 10 hour quality game to 100 hours of mediocrity. The thing is, the loot hunter is a peculiar breed that's supposed to allow hardcore, endgame players to extend the experience for at least several dozen hours optimizing their gear to more effectively combat the most challenging foes. At the end of my roughly 12 hour run in DS3, I could effortlessly demolish any area in this game, and it just didn't reward you for pushing beyond that (even though I'm a lunatic and did so anyway, just to discover a rare glitch that broke my character for being "too good," but that's another post).