Honestly, I don't see how this is any different than awesomenessreminders.com. How are you set apart from that service? This is important, since they already have national press coverage and a userbase. What's going to stop them from pivoting ever so slightly to crush you?
Deeply different, it leverages on awesomenessreminders.com weakness, it becomes easily boring. Our message will be different every time, and not only in the way we present it to you, but also in its content.
Why do you think that's the easiest to attack? i think your point is wrong. i acknowledge that i plainly copied the design but that's not an important issue. Their site design is not one of their weaknesses.
I'm not a designer, but as a consumer I think site design is extremely important. If your site looks like it was thrown up hastily or is a fly-by-night operation, I'm definitely less likely to give you my credit card information. Why is it the easiest to attack? Because I think their design is so bad that it wouldn't be hard to dramatically improve, with relatively little effort.