Well, there are a handful of problems associated with them. The embellished language in the descriptions make people a little wary, but the idea of cataloging certain behaviors and using them to shed light on psychological dispositions makes sense to me. For example, if you know that a person wakes up early in the morning every day and exercises, they are methodical and at least a little disciplined. This test makes more sophisticated and subtle observations. A big problem regarding even what it does right, however, is the dichotomy of each attribute. Introversion vs. Extroversion, etc.
I've seen these used to successful communicate and profile people in the business world but they're not flawless!