Good idea, now just start refining it.

Users love a sparse UI, but you've gone overboard. You need to add descriptions to the different pricings; the labels aren't intuitive. I assume you mean 3 brands = monitor three brand destinations (e.g. youtube.com mentions, twitter mentions, and yahoo news mentions). That is confusing to marketing people. Try to make it more clear that you offer increasing depth penetration for a single brand. The multiple users feature isn't intuitive either. --Neither of these items were adequately answered by your FAQ.

I would revise your FAQ language, it comes across as too chatty and colloquial. Your trying to get into the wallets of marketers, act professional. Your design is clean and well done, now bring the writing up to the same level.