Raspberry pi is good for a few things, but you need to get used to full command line interface first.
The recommanded OS - raspbian default do not start a GUI or Xwindows.
And I am experiencing a much stable hardware(encountered overheat problems) under command line(obviously).

So currently I am using it as:
1. a network bridge
2. command line browser
3. hardware development platform

As its power consumption is low, I am very happy to have an "always on" network bridge as a gateway to other devices at home.
In that way, my internal network have some kind of extra security while I still can connect to other internal systems.
On phone ssh to server to restart, quick fix etc very good
Android ssh keyboard

And I just discovered the benefits of using command line interface browser
Recommend w3m over lynx, for supporting chinese characters.

Last, a quick way to develop SPI, IIC, GPIO with python, over network
So I do not need to connect arduino by USB and compile. I HATE COMPILE.
Will share some setup with SPI on rpi later