Pros
Good contracts, paid on time, good hourly rates
Cons
I had the privilege of working at port express for 10 weeks, brilliant place with a good office team. Sadly the agency were not good. Communication (mainly by text) very much breaks down when you question your terms and conditions, however If its a question that may affect the relationship with the contracted employer they respond within minutes because like all agencies, the contracts are more important than the agency workers.
My contract was emailed using a broken link, twice I tried to speak to them about it, both times they were completely unresponsive. 10 weeks of work and they failed to give me any access to my contract.
Full contractual holiday pay was not given at the end of the term. Twice I pushed the questions of how they work it out using the 12.07% rule, again they avoided the questions and were unresponsive. 10 weeks of work equals more than 5 days holiday.
Be careful with your contract, make sure its explained because they will avoid it like the plague.