First of all, this game is really good and figuring out the mechanics or where to go next is mostly a really pleasant and rewarding activity. Many of the boss fights were fun, the npc's are great (most are better than the npc's of its predecessor Demon's Souls), the parallel the game makes with depression is beautiful and Firelink Shrine feels like home... It's such a beautifully executed concept. But... I hate to say it but i agree with most people when they say the second half of the game is inferior to the rest of it.
After Duke's Archives the game had worn me down; I was tired and saturated - I just wanted to finish the game as fast as possible at that point. And besides that, this game is not as inventive as people praise it to be, since a substancial part of its core characteristics and mechanics came from Demon's Souls - they are basically a copypaste of it. There are a repetition of some enemies, bosses, areas, npc's and even lore elements; the thing that is completely original about Dark Souls is its "open-world" and interconnectivity, which is pretty cool and helps a lot with the execution of the games themes, but at the same time, it gives me a feeling of a very small world so I wouldn't say it is perfectly executed.
Dark Souls, in my vision, wanted to be a improvement of what Demon's Souls was, and in many ways this was achieved - but this is where the problem lies: in many other ways it wasn't.
Demon's Souls was still way more experimental and inventive with bosses for example - every new boss felt like a puzzle to be solved (which I personally like more)... and once solved it would give you an enormous advantage against that boss - Dark Souls on the other hand standardized boss encounters to a single type of boss fights (Bed of Chaos was a poorly executed exception).

Anyway, sometimes I think that maybe in that final stretch of the game when I started feeling fatigued and tired with the game narrative, areas and bosses - my head was in the wrong place for personal reasons. And maybe I should've taken a break to finish the game some time later. Maybe if I had done that I would've enjoyed the second half way better, so I'll keep that in mind and will complete the game a second time someday in the future. Maybe I'll change my opinion, I don't know...

At long last, this is still a great game, better than most things you can find in the game industry nowadays. It has some unique traits and atmosphere, a very rewarding gameplay style, greatly executed themes and a beautiful message.
To everyone that played the game and may be reading this, whether you agree or not with my opinion, don't you dare go hollow!