Basically Harry Tasker (Arnold Schwarzenegger) is a secret service agent whose "cover" is as a boring computer salesman. His wife (Jamie Lee Curtis) doesn't know about his real job until Harry discovers that she is having a relationship (so far, nonsexual) with a man claiming to be a secret service agent.
To sum up, it's Scarecrow and Mrs. King.
The beginning of the movie is smart and funny. There's the usual chase scene, except it involves a horse and a motorcycle and a lot of shopping malls. And there's a fabulous scene where Harry "saves" his wife from her lying Lothario and questions her. It's fabulous because Jamie Lee Curtis can act. In fact, in that single scene, she out-acts everybody in the movie. Which may explain why they decided to have her do absolutely nothing except scream (well, and dance) for the remaining hour or so.
The whole point of the movie is that the wife wants to do something that matters. And the movie ends with her and her husband joining forces (it is very Scarecrow and Mrs. King, a show I loved as a teen, by the way), but at no point in the movie do you see the wife and husband working together. The husband comes up with something for the wife to do, but it mostly involves a sexy interlude and is more pacification than anything: here, honey, this will make you feel better. He doesn't give her any real work, and when she gets pulled into his really, really dangerous job by mistake, he still gives her nothing to do. She screams. She clutches her heart as her husband whisks off in a jet to save their daughter.
It's enough to make Dorothy Sayers grind her teeth.
Presumably, the husband decides his wife is tough and smart and brave enough to be a secret service agent too, but the script never proves to you that this is true. The last hour is standard action fare.
I don't blame Arnold. Last Action Hero proved, to me anyway, that the man is capable (or was) of witty, bemused writing. No, I blame the script writers for this one. They gave up on wit for yet another terrorist plot. Oh, blah.