The generator is a 4-stroke Honda EU 1000i (1000 watts) that runs on petrol. It's really quiet, weighs just 13kg and uses inverter technology so power delivery is smooth. Originally, I bought it to charge the batteries through my onboard battery charger every other day while at anchor--I hate using the boat's engine--but ever since I installed solar panels the generator's main use is to run the odd power tool. It may be a bit of a luxury but it's not a bad idea to have a power source totally independed of the main engine. Maintenance is minimal. In the five years I've had it, it never failed to start, except once, following a long period of inactivity. It's a good idea to start it and let it run for 10-15 minutes every couple of weeks. You can download the operating & service manual from Honda's website and take a look at it before you commit your money. Honda also has a 2000-watt model, the EU 2000i, which isn't much bigger and weighs around 20kg.
-Nicholas