The fact that Google even offered that much leads me to believe that they have jumped the shark with that offer.
Anybody who knows anything about retail would have studied the business model and realized that this was not sustainable. Obvious red flags: 1. Heavy reliance on field sales (the largest expense), which is NOT scalable 2. Exclusive reliance on repeat sales as the key driver of sustainability: this being the obvious case, did Google not do its due diligence and actually surveyed past Groupon customers? Such a siimple survey would have easily revealed the issues of this "local deals" model. 3. Heavy reliance on "small business" owners as the driver of revenue. This is a sensitive and fickle market, where even slight movements in the general economy will cause huge moves in spending patterns.
These 3 points were readily available to anybody with some insight into this segment; Google with all its money must be surrounded by "yes" men, nothing else could explain it's willingness to part with $6 billion so quickly.