I like that they provide an easy way to target specific audience groups, as well we have been able use their analytics tool for reporting our results in ways not available from other platforms (ease of understanding).
We are trying out this product now so it is hard atmpting say how effective or ineffective its working but will update you when i find something helpful! Currently looking into getting paid placements - currently using them solely because no one else was doing what needed done which made sense since thats where my business started anyway :).