I just got back from the movie and thought it was really, really intense and enjoyable. I do agree it's a better action movie/blockbuster than a Terminator movie, if that makes sense, but on the whole I thoroughly enjoyed it and would absolutely sign up to see more movies with Sarah and Dani.
The movie's main problem is that it has too much. Too many characters, too many OTT action set pieces, and too much exposition of things that would work better hinted at but not shown or explicitly told (aka most of the Grace backstory/Dani's future). At the same time, it handwaves major plot points a little too much ("Carl" grew a conscience and has been living a normal life all this time? Really???). I do wonder if some moments got left on the editing room floor for time, but I also kind of think the screenplay was just a mess. More broadly, this movie loses sight of the fact that what made the original Terminator and T2 great wasn't their five hundred set pieces (admittedly very well done) but the human moments in between. And when this movie slows down and lets its characters breathe, it is really affecting, it just needed to do that more. That said, it never drags--it's long as movies go these days but it doesn't feel it at all. In fact it flies by. The adrenaline is fairly nonstop.
Linda Hamilton was the movie's MVP. She gave a really solid, moving performance. Her realization that another dystopian future is upon her in the hotel room, and then her scene with Dani in the woods later, were probably the best scenes of the movie. She just owned what Sarah would be like 20+ years later after having had to watch a preteen John die in front of her. OTOH, Arnold totally phoned it in (I haven't seen the most recent few Terminator movies but this definitely felt like his goodbye/like he's ready to be done with the franchise). I liked the girl who played Dani well enough, but the one future scene where she's the inspirational leader was not great. It pains me to say it since I liked her in HACF, but I didn't love Mackenzie Davis in this. The Grace part was underwritten in some ways, but she didn't do a ton with it either. Not sure how much range she has.
I do love how, even if the future/savior/leader changes, Sarah Connor still ends up raising or at least mentoring that person. And Dani is John, but she's also Sarah. Some really interesting recursion there (though that may well have happened on accident...). I will give the movie props for surprising me with the end--I thought for sure everyone else would die protecting Dani and she rides off into the future alone a la Sarah in Terminator 1, or Dani would be left with Grace, but I didn't predict Grace dying and Sarah and Dani being the duo at the end.
Also, I thought all the callbacks to the original Terminator and T2 were great, as was the end scene, which I take to be a callback to the Sarah Connor Chronicles (really appropriately given the events of this movie).
I would definitely recommend this, and would go again if I had time in the next few weeks.