My main problem with sci-hub right now is that it's stopped adding new content to the website since like 1 or 2 years. Which means if you want to have an up-to-date state of the art, you can't use sci-hub. I personally use the bookmarklet, i'm way more inclined towards this than some random browser extension.
The reason why they've stopped temporarily is due to an ongoing court case in India initiated by Elsevier. I'm not sure this is the best article on the case but basically sci-hub agreed not to post any new articles for a period of time (which has been extended) while the case is ongoing:
They did release a bulk issue of 2.7 million articles a few months ago (as part of the torrent collection available from libgen), but nothing new since then.
