A fledgling five-star rating system for law firms has riled some lawyers, who say that such a system is best reserved for restaurants and movies.

After years of threatening to make law firms accountable for increasingly bloated hourly billing rates, the Association of Corporate Counsel last month unveiled a customer-satisfaction survey—much like reviews on e-commerce websites like Amazon—that lets clients rate their law firms. Firms are evaluated both on their legal prowess and cost. The report cards, which are entirely subjective, are available online to all of ACC’s 25,000 members.

Law firms are not eligible for ACC membership and are unable to see the reviews.

The effort is one component of the ACC’s Value Challenge, a movement launched last year to push attorneys’ hourly rates in line with the actual value of the legal services delivered.

In just over two weeks, more than 1,500 evaluations have been completed for over 500 law firms.

“Some lawyers are cautious, some are concerned, and some are really excited,” said Susan Hackett, the ACC’s senior vice president and general counsel. “It doesn’t purport to measure every aspect of a firm’s performance, but basically it asks the question, ‘Does the firm provide good value?’ Success at law firms has often been determined by size, profitability, and reputation. We want to change that so that the criteria of a successful law firm is how much your clients love you.”

Although law firms cannot access reviews, once a critical mass of reviews accumulates on one firm, the ACC will issue a report to that firm. Hackett compares the five-star system to book reviews on Amazon.com—one bad review will not color 20 positive ones, Hackett said.

So far, the legal community has given the system mixed reviews.

Law-firm partners, on one hand, say that while they welcome more client conversations around budgeting and delivering value, they say the five-star system is oversimplified.

“I don’t think this value index is going to be the barometer as to how well law firms are performing. I don’t think most sophisticated general counsels are going to make their decisions based on the Zagat’s guide for law firms—which is not at all to denigrate the need for law firms to provide value,” said James Westra, managing partner of Weil Gotshal & Manges LLP’s Boston office.