Software Engineer
You will have to code a simple program for half an hour. Then they will ask you simple questions about embedded development. Review your OS book from college (threads, stacks, locks, etc). Garmin works on embedded devices so it's fair that they test on these low level topics. Then one puzzle at the end, google style. I would buy one of those puzzle books and work through some of them just to get the basic concept (generally the puzzle looks unsolvable, will have some unnecessary information designed to send you down the wrong path, etc) and techniques to solve it.
I was only there for a few hours but this garmin LA site would be a nice place to work. It's a small engineering group- very laid back with no dress code or even fixed hours. Nice equipment. Standard corporate building just off the freeway. The management structure is fairly flat so I don't think there is much advancement but if you love just coding, it'd be a great place to work.
The manager at the branch is very sharp so that's good news. The best part of the interview was just talking shop about industry trends and emerging technologies.
I think Garmin has a lot of potential as a company and its diversification will help it keep its edge. I wouldn't be worried about job security at all at this branch as they seem to be expanding their operations.