I've heard good and bad about this airline, good obviously about their service, and bad obviously about their safety.
I had tickets to go SYD-TPE-LAX a few years back on them. One day before I was to leave, they had that horrible incident where one of their 747s fell out of the sky (rear pressure bulkhead failed or something like that). I gave in to hysteria and rescheduled with another line. In hindsight, there was no obvious reason to cancel, but I did anyway just for my own peace of mind.
As far as I know, they have been relatively incident free (aside from the recent 738 fire, but that wasn't so much a China Airlines issue as it was a design issue).
Korean also has a pretty bad rep for safety, but I have flown them several times without incident, and their service was pretty good.
So, I guess it's really up to you.