Kudos to them for joining the professional associations--that's always a good sign. But there are some idiosyncratic punctuation choices on the site, which seems like an odd choice for a proofreading/copy editing/content editing business.
::goes to check own site just to make sure I'm not throwing stones from a glass house!::
Biggest thing I see missing is any note of experience in the (book) publishing industry. Doesn't mean they wouldn't make great editors, but if someone doesn't have industry experience, I'm not sure how you could trust that they could edit a manuscript towards commercial acceptance.