Asking me for 'arguments' on this matter is like asking me to explain why PS:T isn't shit. Yes, I could talk about player agency, about writing, about NPCs, about story and about choices and consequences, but if you were able to see it, you wouldn't need arguments in the first place. With DS it's the same: yes, I could talk to you about its serious C&C, its cohesive world-building, its atmosphere, mood, music, graphics, battle system, and so on, but if you could see it you wouldn't have to ask.
I get all Lyric Suite about this: if you had taste you'd know why it's good without needing a list of arguments. If I /did/ provide them you would go through them one by one and 'dispel' them VD-style, but really, you'd just be discrediting yourself if you did because it'd be like trying to point out to me why Leonardo da Vinci is a bad artist.
Yeah, I've kind of become a shit poster. But you know what? My taste is absolutely impeccable and your remark shows only one thing: that you have absolutely no taste in video games. Why? First of all, you're making a statement like 'shit game' without backing it up, then ask /me/ to provide arguments why this isn't the case. That's probably strike one, considering we have
endlessly and exhaustively debated why this is an important hallmark RPG dozens and dozens of times and a simple search or just mere attention would yield the arguments you require.
But hey, let's play, why not?
A) Shit game
Okay, so, how do we approach this? What makes a game good? To me, a game is good if it is well made, with love and has tight mechanics. In Dark Souls, all things form a whole that builds off each element, all of which complement one another. Music, animations, sound effects, level design, writing, all form a cohesive experience. Dark Souls is well made in this regard and executes a single art style with visionary precision. That's why it's so popular with quite a few employees at Obsidian (and any other company with good taste, naturally). The most important part of what makes a game good, though, is, well, the 'game'. The thing you do. The game in Dark Souls is well-balanced and reminiscent of classic games like the very first Zelda, throwing you into a strange world and leaving it up to you, the player, to make the most out of it. You may go where you will and struggle against challenges, using a sophisticated combat system that requires both player skills and character skill, free to build yourself any way you please and learn to use a plethora of weapons. The boss fights are exciting, the enemies a pleasure to fight and the exploration top notch. I fail to see the shit part but hey, maybe I am just a fucking fanboy who sucks so much cock the jizz is clouding his eyes.
B) Not a RPG (sic)
But what is an RPG?
I got news for you buddy, if this isn't an RPG then what is it? An action-adventure? That might be a valid point, only, ever since I was a kid, the gaming magazines lumped action-adventures together with RPGs. But let's do this, mental exercise and all. So what's an RPG? The problem is that we haven't really found a definition. Hell, to some here, Deus Ex is an RPG when to me, it's an FPS with RPG elements. Same with JA2: RPG to some, to me, a strategy game with strong RPG elements. So what'd you call Dark Souls, if we take my perspective? An action game with RPG elements? What kind of action game has such slow, weighty combat and such a strong emphasis on lore and world-building? I can't name a single one. Which action game has so much exploration and atmosphere, and so many different stats to distribute and items to find and use? Again, I can't really name any. Only action-adventure games of the old school come to mind, things like the first Zelda, Terranigma or Secret of Mana. Except Dark Souls is nothing like that, really: there's far more emphasis on developing your character mechanically than in those games and the action is understated, almost like a violent, intense afterthought that is part of the core experience, but not its sole soul.
So given all that I think it's safe to say Dark Souls is either an arcade game (which clearly it isn't, as it lacks credits and continues) or an action RPG with a heavy emphasis on character building and player skills. So there you have it.