This is our first Raspberry Pi. It has Minecraft Pi and mines at about 1.5 GH/s using bfgminer.
For a 700 MHz CPU and 512 Mb of RAM it does a really good job.
I bought a big class 10 SD card (32 Gb for 20 USD!) so we can store our movies.
The whole purpose is to keep it on 24/7 without spending much electricity or making noise or worrying about it breaking down.
So far the only issue is the baby drooling on top of it…