I've been in Taiwan a long time, and during my time here I have often reflected on my situation as a foreign resident of this country. I'm not just talking about applying for my next visa, or having a job for the next year, but also about living well - about being happy - in Taiwan.
I don't think it's a given that someone from a Western country will be happy in Taiwan. In fact, I have known many people, from many Western countries, who are miserable here. In the end it comes down to your goals in life, your interests, and your ability to adjust to life in a different culture.
I could never grudge anyone for having life goals that are different from my own. This is to be expected. Still, there are many foreigners who could have done better than coming to Taiwan in the first place. They may have had reasons for coming here, but in the end these reasons were never clearly thought out. In the end their life goals conflicted with being in this place, and they would have done better to ask themselves whether or not Taiwan really fit in with their plans.
These are the sort of people who end up disappearing. They take a job here, they make (what they think) are sincere promises, and in the end they disappear. I suppose this is also to be expected. Some of them are very young, just out of college in fact, and they just don't know themselves well enough to be in it for the long haul. Still, they can cause others a lot of grief.
Personal interests also play a role in being happy here. If you have no interests that can be pursued in Taiwan, then obviously you won't be happy here. I have met some foreigners who only like sports that can be played in much colder climates, or who only eat foods that can be found in Western countries, or who can only relate to people with Western interests identical to their own. Obviously such people are going to be unhappy here - unless they go about making some changes.
The ability to adjust to another culture is probably the deciding factor in whether someone is happy here or not. I have met some foreigners who are either unwilling or unable to do this. The truly amazing thing to me is that some of them live here for years - even decades - without ever really participating in Taiwan. They eat food at places like McDonald's or else eat at home, they only talk to other foreigners, and they almost never, ever go out. I can only feel sorry for such people, because nine times out of ten it is fear that is driving them, and fear that is keeping them where they are.
Of course, beyond the general points raised above, there are a multitude of finer points relative to living well in this country. There are things like learning the language, or getting used to the food, or even learning to give people red envelopes at their wedding. No one said living here was easy, but learning to make your life easier can be a joyful process.