1) Reputation. So... the jury is very much out. Traditionally one of the "big 3" services, going back to the 90s, we'll have to see if their quality continues under new ownership. The resume writers I spoke to all knew of CareerPerfect.com and a few had worked for them in the past. They have an "A" status with the Better Business Bureau and a Google search for reviews turns up lots of information pertaining to the flip-side of their business career planning and job search.
2) Age. CareerPerfect.com is the 2nd oldest site I found in my research, and their reputation seems quite solid for that longevity. They are apparently the company "powering" Monster.com's resume service, though I'm not sure what that means in these days of Facebook and LinkedIn.
3) Products. Their website is completely un-user friendly (many other review websites also comment on this). However, they have plenty of multimedia, interactive tools and free content, which is super awesome, but almost makes the resume services feel secondary. Once you dig through all of the other stuff, you see that they do offer a wide variety of products.
Corporate Outplacement Services
If you'd like to view some of their work, CareerPerfect.com has a small library of Sample Resumes for your review.
Also, one thing that I learned in this process is that in order to have a Federal resume done, you have to have the exact job listing in hand in order for them to proceed.
4) Price. Their pricing is confusing, but once you break down the various plans, they're right there in the industry standard $200-$300 range. They offer 100% satisfied or they'll re-write your resume guarantee.
5) Industry Affiliations. CareerPerfect.com is also affiliated with the Professional Association of Resume Writers, National Career Development Association, Career Management Alliance, and the National Employment Counseling Association.