Start to care for the plot in its entirety, and don't just long for action and battles.
I never really cared for Kabuto before he showed up with his army of immortals. Even then he was nothing but a cool, cocky villain/cheep Orochimaru copy with some tricky plan. But the recent chapters really made me 'care' for his character. Furthermore his background feels 'right', in place, it totally fits to what we knew about him up to this point: that desire to know who he really is, to create a perfect self, is something that was always present, not something that Kishi just invented to make him look kind of interesting.
Congratulations, Kishi. One of your most felicitous flashbacks. Even those who don't like those kinds of chapters should've found something interesting, since Orochimaru's hideouts and experiments are always somewhat fascinating in my oppinion.