^YKT & t-motion literally posted one second before I did.
Anyways, personal observation & thoughts:
From what I observed thus far, fan reaction has been decidedly
negative unfortunately.
I myself couldn't help but be quite disappointed too. Nor was there that much of a change really (never reading Yahoo Jp schedule preview again!)
There has been wide-spread expectation for Kazumi to return to k7 (now k8), largely due to a vastly improved handshake number & superior Stage results. This did not materialize, disappointing many fans. Nanase's drop is not exactly a surprise, but if handshake is to indicate anything, Nanase is only behind the top trio of Maiyan, Nanamin, & Saryuringo in popularity. Such placements make little sense to fans.
Akimoto Manatsu's return has been largely expected too, as just a few days prior, her inactive blog suddenly posted a test post, which was quickly deleted. This expectation does not translate into satisfaction with her inclusion in k8 however, as she has been absent from most of Nogizaka's activity, & to suddenly airdrop to k8 status ahead of members like Nanase & Kazumi is certainly to upset some fans.
Another disappointment lies in Hoshino's & Sakurai's continuing presence among k8. I like both members, but it is a fact that these two members have vastly inferior popularity in comparison to many senbatsu members, expecially Hoshino. Management do have the right to push members that hey deem with potential, but in the end of the day, I much prefer a slow & steady rise to the top (like mayuyu) rather than a bold & fast push (like paruru's). Imo, slow & steady produce a more stable fan base & much less hate/anti, while the bold & fast push
might produce a strong fan base but
will result in strong hate/anti. My observation is that Hoshino is not benefiting from this strong push at all, but rather is gaining an impressive amount of hate/anti. It doesn't help that she is more mentally fragile than the other members too. The thing is, she's young, so they should really slow down the push; she still have a lot of time the develop.
Ikoma's continuing as centre is also a disappointment for many fans. Given a choice of two, most prefer Ikuta over Ikoma. Given a choice of many, Ikoma ranked fifth in preferred centre behind Ikuchan, Maiyan, Nanase, & Nanamin. I recognize that she is a very hard working member, but that is also the same for all other members. Mentally & popularity-wise, she is exceeded by at least 3 to 4 members. Controversy regarding Nogizaka's centre will continue unfortunately.
Edit: One more thing is the lack of first-time senbatsu member. If the formation is not going to be popularity-based, might as well give all undergirls a chance to stand in the front row. The two new members, Noujou Ami & Saito Asuka, were both in senbatsu for the first single. The rest of senbatsu with the exception of Akimoto Manatsu are all also senbatsu members from the previous single. This only adds to the underwhelming-ness of this senbatsu announcement sadly.