Reviews are important. That’s no secret. Almost everyone uses them now as part of their pre-purchase research. We depend on them. We want them. And in the time and attention deficit world we all live in, we need them to help us quickly make smart decisions.

The basic premise of online reviews can be summed up as "in numbers, truth.” If you have enough people reviewing something, the real answer will emerge. And it will overwhelm all the cheaters, frauds and manipulators who are posting reviews as well.

But in order for a review site to build the volume of reviews, it needs to focus. If you want reviews on all the hotels in the world, you need to stay true to that mission. Same if you’re trying to be the authority on restaurants. There’s always time to expand your scope later, once you are established, known and successful. This is a simple, but key driver behind the success of sites like TripAdvisor and Yelp. If you want people to come to your site to read reviews, you better have reviews to read. And once they’re reading, getting them to post reviews is pretty easy as experience has shown.

That’s why I was puzzled to read recently that a Danish site called TrustPilot had just raised over $73 million in new funding. There must be innovation here, right?

Well, TrustPilot is indeed innovative, but not the way I had imagined. As far as I can see, TrustPilot wants to review every business in the world (and it’s already pushing into product reviews as well). Nothing wrong with being ambitious, but in this case is TrustPilot trying to be too ambitious?

Let’s look at the numbers: TrustPilot currently has about 10 million reviews of 90,000 businesses … worldwide. Further, it’s organized by overly broad categories such as “Services” and “Transportation.” In a nice feature, it ranks the top companies in each category based on their review scores, but in all the categories I examined, I had trouble finding any companies whose names I actually knew. TrustPilot is a great vehicle to post reviews, but as a purchase research tool, it’s a mile wide and an inch deep.

Sure, $73 million buys a lot of growth. But it seems like long odds against TrustPilot getting enough review volume across all its categories to reach critical mass. First they need enough companies to become a real go-to destination. Then they need enough reviews of each company for the truth to emerge.

My review: in a business that depends on volume, don’t start out by trying to be everything to everybody.