There are enough episodes out to reveal this is definitely worth watching. Good actors, good direction, decent production values and a legit story with compelling things at risk.
It starts slow, which represents typical Apple TV filler or padding in a story that might be better served as a movie. This is frequently the case when a series is based on a single book.
But...
Production values are good. The two leads, Edgerton and Connelly, are both strong actors. There have been other series (possibly ripping off the book on which this is based) that have used this premise and not done well. But we note know that we care about Jason, Daniela and Amanda. We care about Jason2 as well, but for a very different reason.
Alice Braga, as Amanda, is a capable actress although not on the same level as the two leads. Her role increases in episode three. And her character's impact on the mutating emotional relationships is fascinating. Jimi Simmons, still looking like a Christian Slater cousin or clone, is fine as well as Ryan, Jason's (Edgerton) best friend.
In episode one, as is the case in most series like this, it rips along pretty well. It's the later episodes where repetitive exposition bogs things down a bit. This kind of "story bloat" can be a problem. The scripting, acting and intriguing plot may reveal a very good series though, so I'll reserve judgment. By the sixth episode we have a definitive plot shaping up, with some emotional and moral dilemmas causing some intriguing tension. And then our own investment in the characters starts to twist. Are we rooting for the same things we were way back in episode one? Maybe not.
Other reviewers want to take issue with the quantum theory (apparently all the rage in sci-fi, Marvel and Disney nowadays) angle and the Schrodinger's Cat reference in the beginning. Don't bother with any of that. It's mainly foreshadowing and merely puts forth the key premise: two things can be true at the same time; and if you could, would you change a key event in your past. The tech-speak dialogue about super position in quantum theory only serves to make us look too closely at the premise's central concept, which, while important, doesn't need to be beat into us by the time we get to episode seven.
It's a flipped plot line of the old time travel trope of an older version of a person traveling back in time to change events in his or her past. Except here, in Dark Matter, it's much more complicated, and morally conflicted than that.
Time, and the final episodes we haven't seen yet, will tell.
I'll keep watching.
Now, that's my review of this series. If you read further you'll get my review of other reviewers of this series...
There are a handful of one star reviews (and more ratings without reviews). One of them starts out: " I only watched the first episode, but this series is trash." Let me say this: if you only watch one episode, don't rate the SERIES. The other one star and two star reviews are: poorly written, have lots of misspellings, have many grammatical errors, and display a deep lack of self awareness and understanding. This is what this site has been reduced to. Uneducated, preadolescents who have access to a keyboard but can't string a sentence together. Reading the puerile ramblings of idiots who feel capable of reviewing anything is exhausting. Where's the "block" or "delete" button? In the immortal words of Anthony Mackie...go get your juice box and sit in the corner. The grownups are talking here.