Personally, like very personally, I liked the series!
I think that the pace of the drama can't be categorized as slow or fast. The drama sort of follows its own pace. Sometimes it is reasonable, sometimes a bit fast but not rushed and sometimes not exactly slow but not fast either. It varies greatly and of course also depends on what is slow and fast for the viewer watching it.
Because it is not supposed to have spoilers, I will just say that all female characters grow and become better. Ren Ran's growth was moving for me as I loved how she learnt to let go, to accept (but maybe her new love life came a bit too early). Sun Yi He was such a bright character and despite the many drawbacks you will watch, you can still not stop liking her. Karen was also a nice character, strong and weak at the same time. Ding Ding was a very cute character with a mostly cute love life.
Coming to the male characters, I will only mention my favorite, Yu Tian! No matter what he does, as long as he is on the screen I smiled, even when he was heart broken. I loved his and Sun Yi He's friendship (sometimes more than the girl gang's friendship).
The ost was really nice, it actually went with the show . The acting was wonderful, maybe lacking sometimes, very rare times but still wonderful.
As compared to other dramas with female centered plot and female friendship (like Ode to Joy, Dear Missy etc) it may be a little dull... But overall it is a drama you can at least give a try, and if you are going to, please be patient for at least 5 episodes. Good friendship, good romance and good slice of life too.