Pros
I enjoyed some of the chairs that I worked for during my 5 years of adjudicating for the history department. It is fine if you have a stable teaching job elsewhere and you just want to show up to teach and leave.
Cons
This did not have a culture that encouraged lecturers to feel like an important part of the department. Lecturers rarely attended department meetings or worked with TT faculty on committees. Getting more courses or full-time status was very murky, though this is the case in many departments. It was never clear why new faculty were hired to teach new classes when existing faculty could teach them. Perhaps the strangest (and unjust) feature of the history department was /is the so-called K2 classes. These are classes with an enrollment of 115 students. If the class filled above 90 students, lecturers got paid for teaching two classes. If it fell below 90 (say 75) they were only paid for one class. So you could teach double the students for the compensation of a single class. It is hard to overstate how difficult this policy is for instructors.