I loved the system demo and I'm even more in love with the Lisa demo! I'm beyond excited for the final product!
While I had a little easier time with the romance scenes than some of the other commenters (having played both demos I got quite a bit of practice) I will say that I do believe the timing window for a "perfect thrust" to be fairly narrow, and very difficult to keep a combo going at full speed. Perhaps you would consider a difficulty slider that adjusts the timing window? That might alleviate some frustration.