I got mine for a specific job (reading data from one device, logging it, reformatting it, then writing it to another device). I decided it would be worth buying another so my son can learn programming. They are both sitting here, doing nothing. The second one I got is still in its box, so I've no idea if it's 256mb or 512mb.
They took so long to get here - more than 4 months - so I went with an arduino derivative, instead.
They run like a normal computer, just with a media card (like the one in your camera) instead of a hard drive, so it's no different at all to loading up an SD card with linux and booting from that instead of your laptop hard drive. If you have an internet connection that allows an ethernet connection, then you can use it for surfing etc, which is all I've found it to be any good for. I've got a couple of USB wireless dongles on the way so I should be able to see if you can make them wireless. There are only two USB ports so you'll need a powered USB hub to add anything over and above a keyboard and mouse, such as an external drive, webcam or usb wireless adapter. The plus side is that this powered hub can be used as a power supply for the Pi (but it does say you shouldn't do that) so you don't need an extra plug socket.
They are powerful enough to run game software which was "cutting edge" 13 years ago, so should be a good grounding for anyone wishing to learn to program, but as far as I can tell there's nothing to let you develop games at that level. All the programming languages available on Raspberry Pi's Linux flavours are also available on PC (e.g. Python,
Scratch)
You'll need a TV or monitor with HDMI connection - I've tried running mine through a composite connection to TV, it's rubbish.
If you do decide to get one, let me know. I don't mind letting one go for what I paid for it. If I were you, though, I wouldn't bother. It's a novelty item unless you want a computer and can't afford three figures for one.