I think if you are banking on something being simpler and "beautiful" as your key differentiator then you are not in a good place. A lot of solutions on the market are not hard to use and they are very entrenched. Sure, they don't look great but at the end of the day you need to realize this is payroll software. People don't live in these systems like they do with Apple products. Not to mention, most of the current companies will have a trained tech setup your account. You really don't have to do much. All customers want is:

a) Flexible. Can handle my current and future employee payroll needs. b) Accurate. c) Reliable d) Great customer support. This includes people who are very knowledgeable with what Congress is up to, taxes, etc, and can make sure I am always in compliance.

I agree with a lot of the comments above. I am not sure with the ROI is from your system vs. PayChex or ADP.