There is an availability column on each game in your Q. It ranges from "Available Now" to "Very Low". The lower the availability the longer you have to wait for your games. The higher, the faster you get your mitts on them. :D
I have lost about 300 hours of my life to the video game Demon's Souls. It is a very difficult game that requires you to stretch your capability to learn from your mistakes. If you enjoy hardcore RPGs, and respect a well thought out game, then yes, it is good.
However, if you do not have the patience to be able to accept trial and error, you will find yourself throwing your controller at a wall in no time. Bottom line is, if you want a challenge with some perks along the way, then go for it. Otherwise, you'll just end up angering yourself.
Its a not so formal sequel to the action RPG, Demon's Souls. The creators felt that they wanted to fully achieve the goals they missed in Demon's Souls and put them into a brand new world and setting, Dark Souls. Same concept as Demon's Souls, different story.