For short distances within the city or even for nearby sights outside the city borders it is an acceptable option. The air flowing in your hair makes the journey a reasonably pleasant experience. The drivers are often speaking some English and can advise you on local sights, restaurants etc. Don't forget to always agree on the price beforehand. Don't be shy to negotiate and you are most likely to get a better price.

For moto-taxi I would recommend some caution to be exercised. The drivers fit their bikes in unbelievably narrow spaces, zigzag between the lanes and it is certainly not an experience for the faint-hearted. In fact, I consider it a pronounced hazard which needs not to be taken. Moreover, only one person can travel with the driver so for many tourists it is not an option anyway.

Renting a motorbike is sometimes impossible – simply no renting to tourists – and sometimes you may get into dispute when returning the bike as some unscrupulous owners claim non-existing damages. Never let yourself be manoeuvred into using your passport as a security bond for the rental. Driving without a helmet can lead to a fine by the police, regardless whether you drive or are a passenger. You should also check your insurance to be sure that motorcycle ride would not invalidate your insurance.