I have seen unflattering descriptions of log homes as prone to a range of problems that stem from their unconventional nature and the relative lack of fully experienced builders, sub, and workers: inadequate foundations, mold, leaks, rot, greater repair and maintenance expenses, and so on. It seems that the relative risk of error in design and building log homes is greater than with conventional homes, often leading to serious problems; and the logs themselves can prove troublesome due to defects and poor seasoning. I am sure that it is possible to build a fine log home that is well-made in every sense and sure to last; I am also sure that it is possible for NASA to have built and operated the space shuttle without fatal incident.
The contractor I plan to use is out of Montana, and they have been building log homes for something like 27 years. I toured a couple of their spec homes and they look pretty good.