My own experience unfortunately is pretty bad, they're usually very sloppy and badly trained, expect to waste a lot of time going back and forth over corrections or just giving up and correcting them yourself in the end. I also found that getting samples is often very unreliable as they most likely will have a large staff and it's unlikely you'll get the same guy working on your pictures from one time to another. Let's just say quality control is not exactly their strong point. Communication is often hindered by distance, language problems or just plain incompetence. I even had to go as far as to produce a "how-to" video once, just to show them how things are done. Not exactly something I think you should have to do if you're buying a professional service from someone. I guess if you still want to go the cheap third world route my advice would be do your research well or be ready for a whole lot of frustration coming your way.