Here ya go.
Most positive review:
9.0
"I enjoyed Legion of Super-Heroes: Millennium #1. I greatly appreciated the themesthat have been explored in this book so far and eagerly find myself looking forward to where they will lead when the conclusion releases. If you are feeling up for something a bit different than the standard superhero adventure, I'd highly recommend Legion of Suoer-Heroes: Millennium #1"
- But Why Tho? - Charles Hartford
Most negative review:
4.0
"If this is any indicator of what Bendis has in store, however, they'll probably have to wait even longer for a Legion comic worth reading."
-Kabooooom - Matt Morrison
As for reviews from places actually heard of before...
AiPT! - Ritesh Babu - 8.0
None of the major sites seem to have reviewed it, yet.
Which could be a bad sign.
They may be under a gag order from DC until after initial sales.
Edit:
Doing some googling.
https://comicbook.com/comics/2019/09...ew-bendis-lee/
https://westfieldcomics.com/blog/int...nium-reviewed/
But still not finding anything from CBR and Newsarama...