It is very difficult to tell shortly and reality has many different faces.
I have been in Taiwan for 2 years now, working with an ODM (P##A), and know designer working in A##S. None of the foreigners on these 2 companies are happy for many different reasons. (avoid these 2 if you can).
The local designers are more design engineers that real designers. There is little to no emphasis on research and marketing. Usually they use a "shotgun" approach... many bullets in different directions and maybe one might hit the target.
We have a term for the management... we call it STEALTH MANAGEMENT... you know they are there but cannot see them... it is very hard to impossible to get clear directions from a manager, and nobody knows what to do, but somehow things flow (very taiwanese)
If you come to join the electronics industry in Taiwan, you need to have the mindset to work 12 hours a day, and probably the package you get offered is not good. They don't really see the difference between an original idea from an un-original (ordinary? or a copy) idea... they same way, I suppose they don't see the difference between a person that has original ideas from one that prints a lot of pictures grabbed from internet, sticks them on the walls of a meeting room and uses the details to start sketching some concepts... without knowing what they are doing.
I have heard and seen how, for the money they could pay to a high value and skilled designer, they prefeer to hire 2 local designers... again... they don't know what they do... but they will create more sketches that 1 foreigner... and they are not pretentious and don't complain...
If you join as a junior, you will have more chances of being accepted by the rest of the staff. Usually Taiwanese are VERY friendly and nice people. If you join as a Senior, there will be a power game, and many juniors will not like to work with you... either for the language, because you are foreigner, because you are an outsider and shouldn't come to tell them how to do things, etc, etc... Your boss and all the management, in my experience will always support other locals if there is a problem.
If you come to Taiwan you will learn a lot about manufacturing, but you have to decide if that is a skill that will prove helpful in the future. Most designer here use ProE, followed by UX and Catia. I found all these software to be mainly for engineering and will probably affect your workflow and design process.
After crashing against the wall several times, I start understanding the Taiwanese way of doing things. You always have to be very indirect to not make anybody loose face (The boss is always right) and it is very difficult to be proactive (most people will see it as arrogance). You cannot go to someone and teach him/her something... it is better to wait for that person to come ask you. Usually they say that you need to stay behind in order to go forward. It is a hard lesson but seriously requires a change in the mindset to create successful relations here.
Personally I take it as a training... I think that if I can work here, it will be a piece of cake to go anywhere else
About the language... if you work 12 hours (or more) per day, it will require a very serious commitment to learn Chinese. you better take 2 classes per week and study something in between, other way it goes in and out... The language class is something you can usually negotiate with the employer. If you plan to stay for a long time (at least 2-3 year min, I strongly suggest you start learning upon arrival).
I would say it is not worth to come for 1 year... besides the work experience you might want to create a network of contacts and vendors. I would say 2 year MINIMUM.
About the lifestyle: I know many foreigners that go clubbing every weekend and girls usually fall for foreigners. There is a positive discrimination towards white faces here. All these guys usually have a very nice/crazy lifestyle outside of the office. You might have a better time if you are single... otherwise, after working 12 hrs you still need to spend time with your wife and kids... it can be pretty demanding
One more thing... if you are a skilled and highly educated designer, maybe you will want to backup your presentations with some marketing information. People from Sales, Marketing and Management will not see this with good eyes... in their minds, designers do styling and don't know anything about business... they will not be receptive to listen to you and will not feel comfortable that you go into their field.
If you have more questions post them here! maybe I'm forgetting many things now.