Pros
If you enjoy teaching and mentoring the experience you have working with students can be very rewarding. Best part-time positions are "Partial Load" which include some benefits and more hours but are very difficult contracts to get.
Cons
Please Note: I worked for Seneca for more than 5 years and consistently received excellent course/teacher appraisals every semester. So what follows are not the comments of a employee that worked one semester and was not given a new contract. As a general observation of college wide practices (and this is not unique to Seneca) , there isn't any job security for part -time employees and hours and courses taught can change from semester to semester. The following experiences may be department specific and may not be employee experiences in all departments at Seneca. The Coordinator and Chair of the department I worked in lacked professionalism and were inconsistent in their treatment of part -time employees. Part-time employees are not treated very well and could see hours reduced from semester to semester without any explanation given or feedback on their performance. The work atmosphere was referred to by many full time and part time faculty as "toxic". Department management was not interested in the exchange of ideas between professionals and any questioning of the status quo was not welcomed and even punished (you would find yourself with fewer hours or even no contract for the next semester). Staff turnover of part-time teaching staff, during the time I was there, was very high. Of the 20 plus part-time staff I worked with when I started, less than 5 were there when I left.