My wife & I interviewed 5 separate companies (all of which were rated BBB A- or higher) for quotes on replacing our roof. We considered 4 asphalt and 1 well-known metal roofer. Of the asphalt roofers, 3 of them were GAF Master Elite installers like Cambridge Roofing (which means that they can offer GAF shingles with 50-yr non-prorated warranties), and 1 BP shingle installer.
The quote from Cambridge Roofing offered the exact same quality shingles & underlayment as the competitors. The best part, for us, was that they were easily $2000 less than the nearest (BP) installer, and about $4000 less than the nearest (GAF) installer. They were approximately $12000 less than the most expensive asphalt roofer and about $17000 less than the metal roofer that we had interviewed. (So, words of wisdom: be absolutely sure to solicit multiple quotations when you embark on this type of home repair, since there is a huge variance in costs for, ultimately, the same end result.)
Dealing with Cambridge Roofing's representatives was a real pleasure; unlike some companies, I found the employees at Cambridge Roofing to be at all times polite & knowledgeable, and more than willing to explain specific choices that they had set out in their quotations. My opinion is that this company was not out to "up-sell" me on unnecessary products, which is an issue that I had encountered with some of my roofing quotes -- e.g., some other companies (not Cambridge Roofing) tried to up-sell me on more 'Moore vents' for my already-professionally-ventilated attic, and also on an entire roof covered in an 'ice & water shield' which isn't really necessary for my roof's slope.
The tear-down of the old shingles & installation of the new roof went very smoothly. Cambridge Roofing's 7-man crew worked approximately ~2 days in total. They were polite, respectful, and kept the premises clean. As a layman, all I can really say is that the installation job looks good and doesn't leak; no problems observed thus far.
Overall, I would strongly recommend that anyone solicit a quotation from this company. I'm very pleased with the results and the cost-savings to me were substantial.