KCI is an odd airport. Most people that I've talked to about it have never been to Kansas City, except to change planes, which, at KCI, is an annoying experience. The security checkpoints are spread out, so one checkpoint will cover an area that serves five or six gates. So, getting through security is much easier than at most airports.
The gripe most people have is that almost all the services, including bathrooms, are outside security. This causes some frustration among many travelers. The word is, though, that services are being added to the secure areas, including precious bathrooms.
For locals and people for whom KC is their final destination, however, it makes for a very pleasant and easy experience, as in most cases, a traveler will only need to go through security once.
A gripe that locals(including myself) have about KCI is its remoteness. Either, you drive yourself or a rental car to get there, or you pay $40 for a cab, and that's only from downtown.