You will likely lose radio station presets. The clock, trip mileage and mpg displays will reset, bluetooth might need setting up from scratch (if you have it) and the ECU will reset meaning it will go through a learning curve as it remaps to your driving style for first few days after reconnection. If you can keep power on the terminals (with another battery and jump leads perhaps), then you can protect against any possible effects (just be careful of shorting against each other and the bodywork!!).
No big deal if you disconnect power, so long as you are happy to reset a couple of things.