Time to hipster:
Having played the three Souls games recently, I now find myself in the camp that says DaS1/A-team is a tad overrated. The game was surprisingly easy the first time I played it. After that it became downright trivial. DaS2 had me on my toes again. We can argue whether how this was done is cheap or fair, but the resulting effect is what it is. Extreme tracking looks stupid, but given the slow-ish speed and other mechanics FS have chosen for this series, there is little else they can do. It's no worse than enemies whiffing like scrubs because you walked to the side.
Let's talk about the much vaunted environments in DaS1: they're really not all that. A good portion of them are not that interesting to traverse or look at. The best areas are better than the best ones in vanilla DaS2, but that doesn't hold as much weight as the DaS2 haters say it does, not to me. When you add on DLCs for both games, DaS1 gets its doors blown off. And sorry DeS haters, every zone in that game is iconic. Nothing in DaS1 is fucking with with Tower of Latria. Nuh-thing. The also lauded inter-connectedness is a novelty to me, nothing more. It's clever, but it's not doing anything for the core play. I'm not the kind of person who marvels at the fact that you can see one area from another.
Let's talk about DeS. I'm seeing some bullshit about how it's the least atmospheric one? Say what now? There is a palpable evocation of desolation and decay in DeS that the series has not matched. It's haunted, lonely. If you played Shadow of the Colossus, it kind of feels like that world. And this theme runs through the game (give or take some severely out of place bosses) giving it a singular identity, while the other two felt like hodge podges of dark and high(er) fantasy. I don't think there is any area in DeS that isn't thick with atmosphere, can't say the same for the other two. Even at its "lightest" moment (Stonefang), the pervading atmosphere is exactly what it needs to be while fitting into the whole. I thought some areas in vanilla DaS2 were particularly flat and/or confused, lacking the sure hand seen in the prior two games.
Let's put it this way when it comes to atmosphere: DeS is to DaS1/2, as Diablo is to Diablo 2
What you can't take away from DaS1 is the boss fights. I have a special place in my heart for Man Eater, Tower Knight, and Storm King, but those go back to atmosphere. Seeing TK for the first time led me to pre-ordering the NA release. But on the whole, DaS1 has it over that game.
DaS2 gets shitted on and it's not justified against the bigger picture of today's games. It's a lengthy, substantial journey, full of variety and challenge. Few games even give you that assortment of areas, bosses, and enemies, even if they don't all work. It has very little competition in it's sub-genre, in fantasy games, or melee action games. Only the other From games and Dragon's Dogma are fucking with it, and I often think that it's a more interesting game than DaS1, but that could be because it's newer and bigger. That's just vanilla I'm talking about. Add the DLCs and all bets are off. Sunken King alone, my favorite, eviscerates anything gaijin are producing in the ARPG genre. It's a better dungeon trek than any in the other Souls games. The running animation in DaS2 is gay as fuck though.
3: I don't know. The atmosphere doesn't look that hot, so far. Boletarian felt like a plague hit it, Undead Burg felt like it was sacked by an evil army, the town in the demo looks cheery in comparison. I hope the bosses make sense in the context of the areas they are in, and aren't just gangly BB bosses because that's Miyazaki's thing now.