This was probably the last chance for a long time to catch a Jerry Bruckheimer film in the Austrian Filmmuseum (they're running a Tony Scott and Chris Marker tribute at the moment).
Right before Déjà Vu they screened Marker's La Jetée, and the two films corresponded surprisingly well.
Both are about time travel and although Déjà Vu's approach is a far more scientific one, La Jetée (I'm getting kinda sick of all the ´ and ` by now...) seems more plausible. It just never gets the viewer to watch the technology behind the time travel device with any scrutiny - Tony Scott on the other hand tries to explain (by the means of Adam Goldberg's nerd-scientist character) what and how everything happens - with desastrous results naturally - all time travels movies just don't withstand any closer examination - there are too many loopholes and implausibilities - but hey, it's just science fiction.

So forget the implausible science part and just continue to what really counts - it's a thriller - so, is it suspenseful?
Yes, it is, Scott's signature editing and pacing techniques prove to be still the status quo when it comes to thrillers and his pairing with Denzel Washington makes entertaining popcorn cinema for the masses as well as for the film nerds. The structure and technical perfection of Scott's style is indeed remarkable and it becomes quite clear why such an artsy film temple like the Filmmuseum acknowledges Scott with an own in memoriam program (although their choice of films shocked me a bit...).

I won't expand on the plot because it's quite hard to give a satisfying synopsis without spoiling anything - just this little corner facts: Déjà Vu takes place in New Orleans on Mardi Gras when a ferry gets bombed. Denzel Washington, playing a local ATF agent, consults the FBI in their own investigations that uses rather futuristic means.
I think that's all I can say so far, but watch it yourself, if you're in the mood for popcorn-level entertainment that is a bit smarter than your average superhero movie.