Maybe Eva will be good experience that you can use to get a job with another airline in a few years, but probably not one that requires you to be type-rated, as I believe you will convert to a Taiwanese licence and get your type rating on that licence - Taiwan is not a member of ICAO so I think you would have a lot of difficulty putting that type rating on any other licence. Therefore if you were looking for a job with another B747 or A330 operator, you would probably have to do a full type rating again for it to be valid. It may be an obstacle when you look for another job, even though the widebody experience will be helpful.
I would also be interested though to hear from anyone who has worked there before and if this caused any problems getting another job (or were you able to put that rating on another licence?). Of course there are quite a few airlines who will take non-rated pilots (e.g. Emirates) but probably more that are only accepting type-rated applicants.