Brad Pitt in Ad Astra

Courtesy of Venice International Film Festival

James Gray's much-anticipated sci-fi thriller "Ad Astra" had its world premiere Thursday at the Venice International Film Festival, so the first reviews are finally here.

So far, things are looking good for the Brad Pitt-starrer. While the space film wasn't necessarily universally loved, many critics have shared very glowing reviews. In fact, the review aggregator Rotten Tomatoes shows that with nine in so far, the film has a Tomatometer score of 89%. Those who loved it were also vocal on Twitter; there was even talk of Pitt and a possible Oscar.

Of course, it's always hard to get everyone on board. In spite of all the rave reviews, some critics found themselves a little underwhelmed by the sci-fi flick (hence the sub-100% rating). They've been vocal as well, explaining where they felt "Ad Astra" missed the mark.

First, here are some of the positive early reviews:

And here's what the critics who are a bit underwhelmed are saying:

"Ad Astra" opens Sept. 20, so you can watch it and decide for yourself whether it's amazing or a little disappointing.