"Yes, measuring value proposition for consumers can definitely be difficult - but I think ultimately you have to take a stance on it, and have a strong opinion about what works or doesn't. For a search engine, you want to create a bunch of metrics that try to get at whether or not people found the result they were looking for. For dating, you want to figure out metrics that determine if people are having good dates, and find the right match. This is a hard problem overall, but either way, the number of users that YOU register is probably not the right one ;-) Etc." - Andrew Chen