My Take
Overall, I think Quizizz is engaging for students and provides useful data for teachers. I think it's best if used mindfully - too often and I fear students would not take it seriously (my similar thought on most game-based tools). My only complaint is that I have to turn off my projector or switch screens so students do not see the live results. I did not realize that the first time playing with students and it put pressure on some of my students who needed more think time. Now, I usually open it in a separate tab so I can minimize the live results and put a "do now" activity up for early finishers.
How I Use It
Quizizz was one of my favorite tools this school year. Similar to the questioning in a Kahoot game, Quizizz instead delivers the questions directly to student devices. This allows for students to work at their own pace rather than whole group led. This made a world of difference as I noticed sometimes students would answer without actually thinking just to be first in a Kahoot game. In between questions are fun memes, too! My classes loved this, but I understand the potential distraction depending on the students. Quizizz integrates nicely into Google Classroom, has easily exportable data results, and was easy to set up. There is also a library of premade games to edit and utilize; so helpful for teacher time crunches. I used it as a pre/post-test, bell ringer activity, and even assigned a game a homework!
As with most web based applications, a reliable internet is a must. It is a platform agnostic tool, but students do need some kind of device available to them. Also, as with any formative assessment tools, high-quality questions are a must for effective data.