Beyond that, though, there are many personal benefits to a life of voluntary simplicity. As more and more people are discovering in this age of constant consumption, more stuff does not make us more happy, and in fact can take away from our happiness.
With less physical stuff in our lives, we could have more of a sense of calm. We'd have less to clean, and it would be easier to find the stuff we actually need. We'd have more money, since we wouldn't be spending it on so much stuff. With this extra calm, time (not spent cleaning), and money, we could then focus on the more important things in life, whatever that is to you.
That being said, getting rid of stuff is not easy. Between this book and some blogs I've started reading lately, I've been thinking about uncluttering a lot, and I can now tell you from experience: it's hard to get rid of stuff. It seems silly, but it's so easy to form attachments to material possessions. I had three pairs of slippers, even though I hardly ever wear slippers, and I couldn't bring myself to get rid of any. I finally threw one of the pairs in the to-be-donated pile, but it was tough.
I think it's worthwhile, though. I went through the clothes in my closet last week, and this time, instead of just donating stuff that didn't fit me (not much, since my body isn't really changing shape), I donated stuff that I didn't wear. There's still too much stuff in my closet, but I can get to all my clothes now without struggling with the surrounding hangers. It's a nice feeling.
While this book didn't really do anything for me (it lacked practical advice, and was rather repetitive), there are lots of other resources out there if you want to learn more about getting rid of your clutter and living a simpler life. The best one I've found so far, which is full of both inspiration and practical advice, is Unclutterer. The author of that blog, Erin Doland, even wrote a book, which I haven't read yet, but I'm sure would be really awesome.
In addition to Unclutterer, I recommend checking out The Story of Stuff, where you can watch videos showing, in very simplified form, the problems with our system of consuming stuff.
I forgot to take before pictures before starting my attempt at uncluttering, but I'll probably take some pictures of the stuff I'm donating, and after pictures if I accomplish anything impressive. I encourage you to try it as well, even if you just unclutter a single room, or just a closet! You could blog about it, or post pictures, and link to them in the comments. Have fun!