http://www.epipheo.com/ is another company that does explainer videos. They have 8 different animated styles. I've never worked with them but I have seen their videos on a bunch of sites and always enjoy them.
For those first timers working with a production company, if you have a very clear idea of what you want your video to look like - be as specific and detailed in your communication as possible. Mood boards and story boards, even if very very low fi, will help reduce the amount of iterations which can be extremely important depending on how the company charges.