Caveat, I'm not the target audience, (and hadn't read the short story source first) so for you to calibrate: I rated Jumper at 7; Avatar at 6 bumped up to an 8 for CGI; and Last Airbender at 3.
This film has all the individual elements for a great time: The opening draws you into the story; Blunt is engaging and sensual; Stamp is villainous; Damon/Blunt have fabulous chemistry including a great meet; initial mystery, sophisticated humor, snappy repartee, wonderful score, and superb scenery. The supporting characters are well cast and acted. However, the thin plot doesn't sustain the whole movie, and it takes too long for the minimal plot to unfold, even though there are myriad chase scenes to divert you at first.
The movie was seemingly created for chase scenes, with a poorly contrived reason for the "boy meets girl, boy loses girl but continues to search for her storyline", tossed in to justify all the chasing. In attempting to make everything mysterious, the audience is kept as ignorant as the characters to the point where it became "THATS the reason he's been chasing after her? How DISAPPOINTING!" when the cause for separation is unveiled. The secret meetings which presumably either advance or reveal the mystery were annoying instead. Finally, in the last portion of the movie, the opening doors and running become so repetitive, you can feel like the Blunt character, who has her hands over her head and is screaming. The ending is abrupt, contrived and disappointing, a veritable deus ex machina version.
Conversely, my companion who loves everything sci-fi or sci-fantasy, and reads Phillip K Dick (including the short story on which this was based) rated the movie "excellent" as opposed to my "ok". Even though the movie diverges from the short story, he suffered no confusion or disappointment with the story line, big reveals, or ending. He also thought the cast, romance, and humor were great.
We both agree--do see the movie on the big screen as it certainly enhances the suspense and startling moments (political crowd scene, adjustment scene, car crashes, action scenes and finale) and shows off the great NYC locations. He says go ahead and pay full price,the movie is worth it