I just finished reading the manga so thought might give this a try despite the bad reviews, and I get why people didn't enjoy this cause it was so weird and different from the original work.
I think Hirotaka's character was completely different, and Narumi lost some of her charms, too. Totally don't understand why they decided to let Hanako and Kabakura be cameo appearances while these 4 are the core characters, I love their relationship so much.
To be fair, I don't think it's that bad, I actually like the new Sakamoto character, he is a pretty hardcore otaku and it was so funny every time he appears. The musical sounds nice, I love the dance between Narumi and Kabakura (despite it being so weird).
The acting was great, I love Nanano, she is so pretty, sad to not see more of her.

So I guess just watch at your own risk, don't take it too seriously and you might enjoy it more.