I'd be very careful. Insurance isn't an "investment" if you take dying out of the equation. If you die early on in the policy, sure you have a great return, but ya not so great having paid your life. Personally, I invest in investments, and use insurance (term) to protect against potentially dying.
One thing to watch out for is the person you are buying this policy from, typically better if its a financial adviser, advising you on various options with pros and cons presented. If you are being sold a policy from an insurance agent/salesman (regardless of what his title is), you should definitely take pause. If it's an insurance salesman, you can be 95%+ confident that they have no clue of whether or not the policy is actually financially good for you. Sure their company has perfected their marketing material, sales pitch,and counters to whatever you say, however, it doesn't mean they have your best interests in mind. They've been spoon fed to believe it's a great product and that they get fat commissions. I know, I used to work as one.
Another thing to consider is that most people don't have enough information to understand truly what is best for you unless you're using a solid financial planner/adviser.
If it was such a good deal, more people would be doing it, don't let any marketing verbiage tell you any different. There are only so many markets that the underlying cash can be invested in. I do however think for estate planning purposes these can be a great opportunity given the death benefit is not taxed.
These policies are very confusing, so make sure you do your due diligence beforehand.