I ended up seeing this a few days ago.
Mixed review here. T6 is not as good as either T1 or T2, but it is better than T3 and much better than both T4 and T5.
I loved the cast across the board and all of the characters. It was great seeing Linda and Arnold again. Grace and Dani were good, and Dani would be a fine character going forward.
I won't try to make a comprehensive list of the problems that I had, but there are some that are rather large. For example, I would say that the handling of the military situation contained multiple plot holes, such as it was in the absence of further information about who the Major was, what unit he was attached to, and what exactly his relationship with Sarah was. They breached the security of a military base and were rewarded with a fighter escort. That made no sense, and I sincerely doubt that your average Major has the authority to order fighters to protect a military transport in US airspace that has been commandeered by an armed civilian party that includes wanted illegal aliens. Moving on from that, if this transport was worth protecting so much, surely there would have been some infantry dropped near the dam in a timely manner where the transport had crashed in a big, huge, dramatic fashion and the fighters had been lost. Where was that infantry? And while we're at it, wasn't anyone else besides the new Terminator interested in following the stolen helicopter from the border detention center?
On the subject of MacGuffins, in T1 John Conner is just a MacGuffin. He's more than that in T2, as an essential character and Terminator whisperer. T6 evidently exists in a different timeline from either T1 or T2, because it's no longer about stopping Skynet. We have a new MacGuffin, protecting the future Dani. I can't tell whether it's deliberate and/or ironic, or not, or just an oversight, but I think it's worth noting, in the context of the stance that T6 apparently takes about females having more to offer than just their wombs, that Grace protects Dani by producing a secondary MacGuffin from her own body, the EMP [sic] device. In a sense, that reduces Grace just to a MacGuffin delivery system, and I was left wondering why the filmmakers chose that route instead of electing to dig something out of the inside of Carl to accomplish the same thing, especially since T2 established that there were powerful reactor parts in the 101 body.
I found much of the action implausibly over the top, particularly in the crashing transport.
Not sure what letter grade to give it. Not an awful film. I'm glad enough that I saw it on the big screen, so there's that. Seeing Arnold and Linda one more time was worth it.