The Pi is wonderful, depending on what you intend to do. If you're looking for it to act as the be all, end all computer in your life, you'd probably want to buy something more powerful.
Having said that -- the Pi can be used for TONS (literally, tons) of things... it all depends on your imagination and linux/programming skills.
I have connected my Pi to an Arduino and have built a robot that moves around, speaks to me, takes pictures, answers emails, sends me text messages, fetches the weather, tells me random jokes, etc. etc. etc. For that purpose, it is perfect. It was also cheap for me because I had most of the stuff already lying around.
While you can connect peripherals to it, I simply use VNC server to tap into it. Sure, it's not as fast that way but I don't have to use extra keyboard / mouse / monitor. Also, this allows me to keep it tucked away nice under the coffee table and the wife doesn't complain that way
One word of caution -- it's not like you take thing right out of the box and turn it on. You'll need to set it up, which can be time consuming depending on your knowledge already.... but, this is why the thing is so cheap... you get bare bones and force yourself to learn the rest.
