The problem is not the Act structure, but the implementation. Story wise, almost every dangerous element built up in those first 2 acts have been destroyed. For instance, we learnt to fear the Pit back in chapter 2, but it turned out to be just an itinerant club with a drug lab on the side. The intended thrill is not there when you pictured a clash between the best ghost in town versus an almighty corp but then all of them prove to be a bunch of amateurs who just can't stop from taking poor decisions after poor decisions. Baynard/Meredith can't be taken as a serious threat anymore after witnessing how they handled the search for the MC, who is constantly roaming around the city for the most flamboyant reasons without being detected by his chasers (but is easily spotted by news anchors and spoiled brats), and the black-op at Victoria's which is just a bad joke. I'm not going to analyse every single move but before chapter 8 almost everything in that plot and in characters' actions made sense and felt credible story-wise, while from chapter 8 onwards the opposite is true.
In that context, while it's true the plot has indeed advanced and we are on our way to the final battle, the massive amount of sex encounters that needed a build-up based on our MC going around undetected it's just too much to keep our interest and suspension of disbelief intact.
