If you want shore diving beyond the limits of your hotel, you need a pick-up truck – you can’t transport tanks on a Scooter.
If you want to get about, but stick to downtown then a Scooter will work. The further you are out from downtown, the lower the quality of the roads though. They are ‘good enough’ in most areas, but don’t expect to go into the National Park.
Some travelers to the island consider the scooters dangerous due to the roads and poor drivers. The roads are ‘not that bad’ and any kind of poor driving is not specific to the island. Generally people are simply speaking to the higher risks of ‘two wheel freedom’ and the idea of ‘high incidence rates’ of accidents with touristic rentals. If this is what you want, bear those things in mind and please be careful.
Scooters are easily backloaded with a passenger and they are not at all a great idea when it has rained – the roads will be slippy.