Yes, its easy and just behaves just as any other linux. Compiling the source takes several hours and I would also recommend to copy the blockchain data from somewhere else, but once synced the pi is staking smoothly.
If i want to buy such a micro pc, should i buy raspberry pie or banana pie? Banana has better technical specs.
I have a staking pc but it clearly takes more power than a raspie .
Well the additional RAM won't bring any advantage. The dual core of the banana will probably make it more responsible even on heavy load and also compiling the source will be faster. If I would today decide to buy such a device for general purpose I'd probably have an eye on the banana.
However, if you really only want to use the device for staking one could argue that with the banana you're actually buying to much power for the task.
EDIT: yeah basically what Subtuppel wrote while I was still typing