Pleasant people and workplaces, lots of communication - but low pay, and no permanent position yet
Pros
When I was available 5 full days a week, John Leonard was able to find me positions to fill most of my time. Most were positions of one to a few months duration (long enough to get a sense for a workplace) and most were reasonably challenging jobs in which I was able to pick up some new skills or hone the ones I already had. In my experience, if you keep in contact with them, they will keep in communication with you and keep you in work, and are pleasant and appreciative of a job well done, as well.
Cons
My pay has reliably been only $8-12/hr depending on the job, and in spite of the claim that a good number of jobs might yield a permanent position, this has not happened for me. Of the 10 or so fellow John Leonard temps I've gotten to know, only 3 have landed a permanent job through a temp position. However, I believe this is simply a mark of the economy and the times - it's often cheaper for companies to maintain a revolving stable of temps than hire permanent personnel for entry-level jobs.