*UPDATE* The Bitstorm website has been offline for several days now, leading to the assumption that it was a scam all along.
Bitstorm almost seems too good to be true due to the interest rate they are offering. At 10-15% daily, it is much lower than obvious scam sites that promise hundreds or thousands of percentage points of profit in a matter of days. However, it is significantly higher than the 2-5% offered by many longer running services. We've done an in depth search through multiple search engines looking for scam reports, and have not been able to find any concrete proof that this is a scam. There is however, ample speculation and comparison to scam sites people have seen in the past.