Pros
A lot of smart guys work here, and the atmosphere is generally jovial. Olathe is a very nice area, and there's no commute to speak of. Compensation is good for comfortable, middle-class living, and the benefits packages is great and takes care of everything you'll need. The work is interesting (of course, that depends on what you're working on), and new products come along quite frequently. There is some room for creativity and new, original work, but not much.
Cons
Garmin has grown a lot in the past few years, so the company has lost a lot of the atmosphere and feel of being a small organization. Now, there are lots of meetings for team leaders, and developers working on critical features can expect frequent interruptions from email and conference calls and bug reports. A lot of red tape is being put into place for developers committing changes to shared code, and, although code review is a good thing, it's being implemented in a cumbersome manner. This is mostly due to the outdated source code controls system that's still in use here, and which Garmin seems to be stuck with. It is also immensely frustrating to be working on a constant stream of products that are just not innovative enough, and not bringing anything new to the table for our customers (well, as far as the PND and cellphone markets go). Garmin seems slow to pick up on new market trends, and is happy to just keep on pushing out products that are merely a slight variation on a theme. This can be an issue for any developer who actually cares about the products he works on.