What it is is unforgiving, obtuse, and maybe a little mean-spirited at times (the Catacombs and New Londo Ruins being so easily accessible is a pretty mean touch, or an outright game design flaw depending on your perspective).
I'm a bit conflicted on this as, while it can certainly be frustrating (I myself spent a good 15 minutes repeatedly dying to the skeletons by the Catacombs entrance on my first playthrough), I see it as an important part of Dark Soul's design, particularly in the context of game design trends at the time. In 2011 many games had adopted an approach to game design that included lots of hand holding and "playing it safe" to prevent players from getting frustrated: Jonathan Blow, developer of Braid and The Witness, talks about it in this 2012 interview.
The downside is that those kinds of games don't create the conditions that allow for that sense of relief and satisfication that you mention later - the player just holds forward and follows some waypoint to the next set piece, completes the set piece that was effectively spoonfed to them, rinse-repeat. By contrast, Dark Souls instills a sense of danger, that it is very much not safe at all and that one has to explore the world carefully and pay close attention to the environment or risk being crushed by a much more powerful enemy, or being ambused by five undead dogs at once and overwhelmed. I certainly don't think it's perfect (the dragon that breathes fire on the bridge at the start, and a lift that ascends into some ceiling spikes immediately come to mind as going too far), but I think it largely accomplished creating this sense of danger and tension without consistently feeling cheap or mean spirited.
I'm a bit conflicted on this as, while it can certainly be frustrating (I myself spent a good 15 minutes repeatedly dying to the skeletons by the Catacombs entrance on my first playthrough), I see it as an important part of Dark Soul's design, particularly in the context of game design trends at the time. In 2011 many games had adopted an approach to game design that included lots of hand holding and "playing it safe" to prevent players from getting frustrated: Jonathan Blow, developer of Braid and The Witness, talks about it in this 2012 interview.
The downside is that those kinds of games don't create the conditions that allow for that sense of relief and satisfication that you mention later - the player just holds forward and follows some waypoint to the next set piece, completes the set piece that was effectively spoonfed to them, rinse-repeat. By contrast, Dark Souls instills a sense of danger, that it is very much not safe at all and that one has to explore the world carefully and pay close attention to the environment or risk being crushed by a much more powerful enemy, or being ambused by five undead dogs at once and overwhelmed. I certainly don't think it's perfect (the dragon that breathes fire on the bridge at the start, and a lift that ascends into some ceiling spikes immediately come to mind as going too far), but I think it largely accomplished creating this sense of danger and tension without consistently feeling cheap or mean spirited.