I haven't played 3, but I say 2 over 1 because it actually fucking works. You can't get randomly trapped in way too powerful zones, corpses disapper so you don't trip on them, you can't get cursed so badly you have to backtrack the entire known world, etc. Also, whoever designed Blighttown took the "bug infested swamp" theme WAY too literally.

The interlocking map is certainly "cool", but as far as gameplay is concerned, it's pretty much the worst way to lay out a world, because you can't easily get from one place to another, and it will very quickly confuse everybody. There's one level, new londo ruins, that you can't attempt without using a pretty rare consumable each time, and when I was attempting it, firelink shrine was extinguished, meaning I had to run for like 5 minutes before each attempt on top of the consumable problem.

Hbomberguy has a great video about it, you should definitely check it out if you are interested in the games, he obviously puts it much better than I can