Not maintenance free, but not too much maintenance, assuming that you get a decent-quality scooter (not a $300 Made-In-China special). You'll change the engine and transmission oils more regularly (mile-wise) than you would on a car, but the actual amounts needed are tiny and it's really easy to do. You'll want to check tire pressure often. Scooters and motorcycles are usually harder on batteries than cars, so you may need a new battery every 5 years or so. Things like brake pads, spark plug, transmission belt and air filter will need replacing eventually, but not every year or anything.
Mostly you just gas+go.