It's not awful, but the paid version doesn't have nearly enough features to be worth it at this point. The art and animation are very well done, and the voice acting is pretty good too (though there isn't much of it).
Moreover, there doesn't really seem to be much skill involved? As far as I can tell there are very few real choices to make in terms of technique for trying to make Naomi orgasm. Basically you just keep going until she has at least two orgasms (and in the only ending I've been able to get, she still begs for more...). Yours don't seem to be limited (unrealistically), so who cares how well you do? Just keep going!