It is a moster, though I was able to pass it on the second hardest. I'm not even going to bother on Chaos Mode. I only need one more thing to do to get my platinum trophy.
You can find pretty much everything you need to know about the game from the wiki, including world tendency: http://demonssouls.wikidot.com/world-tendency ...but to make a long story short, I wouldn't even stress yourself out attempting to do everything on the first play-through. Heck, it's actually impossible to do so... like in one game you might do missions for a character, and in the next you might assassinate him. So don't even start worrying about trying to be a completionist until your first new game+.
As DaDakota said, you can sometimes get better controls depending on the game. Definitely for WRPGs and strategy games, and probably for FPS games (maybe up to opinion, although I much prefer M&KB). Along with that, you'd get better graphics and framerates. Mods can add a lot to games. And PC games (via a service like Steam) can be MUCH cheaper than their console counterparts. Plus you could still set up your PC to "play" like console (controller, hooked up to HDTV, etc.). I played a couple, and they were pretty good. I haven't played some of the best yet (e.g., TWEWY), and I've more or less ignored the handheld offerings from Atlus. Certainly are more than on the PS3/360, but I'm still left wanting a little more. And as good as some of them are, part of what I'm wanting is some JRPGs that can take advantage of the power those consoles have to offer. Not so much old school mechanics, but new designs that are possible due to new technical capabilities.
PC is easliy king of fps for controls, consoles need aim assist. I advise anyone to download woflteam from aeria, free game, to see what I am talking about.
I personally never liked M&KB, I hate clicking people to death, I prefer pulling a trigger on a controller. I had mods, at least for consoles, people tend to **** up everyone elses time who can mod their 360. I also always have trouble with computers breaking down and whatnot. I just prefer a console. I also don't have any friends that play on a PC and I do most of my gaming with friends.