Welcome to Taiwan. A valid International licence is a good start. If you want to own a scooter in your own name, You need an ARC. If you have an ARC and a valid international drivers licence, you can get a Taiwan licence for a bit of hassle and running around. Look elswhere in this forum, I think “Got my car and motorcycle licence” It’s a sticky in “Vroom Vroom”. Or try the search function.
You will get varied opinions about the level of safety here. Some people would never dream about sticking their necks out in traffic here. It’s world renouned for being chaotic at best. The rule of law is not adhered to at the best of times. Anything can happen at any time. The weather can change on a dime, the pollution is sometimes awful in the cities, etc. There are something like 1.6 motorcycles for every person in Taipei alone (please correct me if I’m wrong). Traffic is crazy. It is dangerous. Only you can decide your level of comfort with it. Some people drive for years and never have a problem, some people are accident magnets.Have you ridden motorcycles before? Even if you have, It’s a whole new ball game here.
But: Having a motorcycle affords you a sense of freedom. You can leave the big smog after work, and go to the ocean, or the mountains, or just away for some quiet time. If you feel adventurous, you can go on any number of good day trips around the island, or even take a week and see a good portion of it. You can go to places that are hard to go to by the (excellent) transit system alone. you can go shopping and carry a lot of stuff, if you wish. You can do it when you want (within reason) and where you want. You can get to work in five minutes by bike, or twenty by transit.
The costs for a basic scooter are not that prohibitive. You can get a good used one for around 10,000NT, and anything that needs fixing on it can be done for cheap. Mechanics here are mostly honest and if you have a problem with their work, they will usually fix it without grumbling. If you want a proper motorcycle, costs may go up a bit, but not much.
I recommend a scooter for daily use and day trips, and a motorcycle with gears and such for more challenging rides. Scooters are very utilitarian, motorcycles are a little less so. Up to You.
If you want time to decide what you want when you get here, then rent one!
There is a shop called BIKEFARM in Taipei somewhere, where you can rent for a reasonable fee. The proprieter (sp) is a foreigner who is renouned to be trustworthy and honest. Find a link on this site somewhere. Then you can see for youself!
hope this helps, good luck!