It was very easy for us as an agency, because we had already done all of our work before they started working in this project - so there were no problems or issues that arose during implementation phase! I think it is important when choosing such services not only look at price but also consider quality & functionality provided (and lack thereof).
We would like more control over automation process from management side if possible without having IT team involved each time something needs changing/fixing etc. But overall experience has been great- both client got what exactly he wanted out of platform usage (we helped him find his target audience via Facebook) which resulted into increase revenue significantly faster than expected after launch date! And now clients are happy users who love using product daily :) As mentioned above you should be looking how much can do your job yourself instead getting someone else doing things while waiting till everything works perfectly ;) If anything could have improved my opinion about service provider's professionalism level and communication skills.