But anyone who has ever seen Terminator 2, has to look upon Terminator Genisys as a mild letdown. Still, it's better than Terminator 3 (2003) and it's good to see Arnold Schwarzenegger reprise one of his signature roles.

Characters go back in time, either to prevent things from happening or to make sure they do. But Terminator Genisys is very much of the moment in its concern that technology is getting out of hand. The Genisys of the title is a new operating system that is going to link up the entire world - and then wipe out civilisation.

How exactly the operating system will do this, or how people's signing up for the system makes it easier for them to get blown up, is not made clear. Just accept that, as one character puts it, "People are inviting their own destruction through the front door, and they don't even know it". But now you've been warned, so look out.

Terminator Genisys is convoluted. We get scenes like the one in which two people explain the same complicated concept to someone four times and the audience still doesn't have a clue.

The year is, well, the year is a lot of different things here. But following a recap of history, in which the TransAmerica Pyramid and the Golden Gate Bridge are obliterated before the opening credits, the movie formally begins in 2029, with John Connor (Jason Clarke) leading the human forces to free the Earth from robot rule. The Earth, or at least California, is a dark, desolate place - everything is burnt out, falling down and ugly.

Connor sends his right-hand man, Kyle (Jai Courtney) back to 1983 to protect his, Connor's, mother, who is only 20 and has not yet given birth to John. Kyle finds that Sarah Connor (Emilia Clarke) is already feisty, having spent most of her young life warding off terminator attacks with the help of her own terminator (Schwarzenegger), whom she calls Pops. Pops is looking a little older these days, but that's because the terminators are made with real human skin, which ages. Still, as Pops says, "I'm old, but I'm not obsolete".

Realising they must stop Genisys, the three decide to go into the future. Eventually, they decide on 2017, because that is the date that Genisys is scheduled to launch.

Playing a robot, Arnold doesn't engage much in small talk. Terminator Genisys is still at its best when Arnold is on screen. Those moments without Schwarzenegger are particularly noticeable here because Emilia Clarke and Jai Courtney, for all their winsomeness, are not quite enough to carry a whole movie alone.

The movie's notion that time is never a fixed entity is all well and good, but it conveys a sense of futility.

There are too many shootouts involving robots that can't be injured. It's dull. Still Terminator Genisys is a "Terminator" movie that feels like a "Terminator" movie, more than Terminator 3 did. The San Francisco Chronicle