I love the idea and think you are on the right track with easy setup and SMS integration. Try and look at it more from the customer's point of view; they are basically signing up to be spammed, correct? A small business may want all those features you listed (remember that features don't sell, benefits do), but they aren't going to buy if you don't show how customers will also benefit and opt-in in droves. SMS is simple for a lot of people to use, but it might be helpful to explain how people actually opt-in.

The website is too word heavy; try asking a few friends to read a paragraph you have written, then summarize it back to you. Usually you'll get a more concise answer that could be used instead.

Like everybody else, I recommend you re-evaluate your pricing. The mailchimp example somebody mentioned is perfect. The paragraph you have between Indicative Pricing and Pricing is completely unnecessary.

The How It Works page also needs to be pared down. The goal should be to get small businesses to sign up, then have it be so simple to use that the operation acts as a guide. I would change Sign Up to be a link, then have Register Customers (signs up telling them to use mobile phones, register on the site, NO manual input from the business owner), Tailor Marketing Offers, Reap the Benefits. Or something similar, it just needs to be simplified, a lot!

Again, I love the concept and hope you have the drive to see it through!