One issue Groupon have is to review their cut to the lower, recurring complaint is the fact that they charge almost at least 50% of the sale, for most small businesses the discount + Groupon cut is just unsustainable.
They also need to stop the hard sell tactics reported by some small business owners. It's unacceptable to lie and say they aren't able to limit the number of groupons sold, or not explain up-front that the minimum split groupon will take is $10. It really seems like they prey upon the less savvy business owners, and it will cost them in permanent reputation damage.