I'm not a car-guy.  I admire those that are.  Cars are complicated pieces of machinery, require a lot of love and attention, and can get some women to lose their clothes in zero-to-sixty.  I understand why this series has becomes so popular even as its stars departed for bigger careers that didn't really happen—it's all about the cars and it's all about speed.  But if that doesn't do anything for you, then what should be exciting for everyone—the races—are nothing but brief rushes of energy between laughably bad drama.  As for the original character returning, that's really the "bonus" since they were never the main draw.

For those that need a plot (the film says it was written by Chris Morgan but I don't think that's true; I don't believe this film had a writer), Dom Toretto (Vin Diesel) has returned from his life on the run to track down the man that killed his loved one (if you're a fan of the series, it's kind of surprising who they kill so I don't want to spoil that for you).  It so happens that Brian O'Conner (Paul Walker), who can apparently do just about anything and still be in the FBI's good graces, is tracking the same baddie.  Dom wants the guy dead, O'Conner wants him captured.  There's bad blood between them (because conflict is good) but they can't expose each other since they're both trying to infiltrate the bad guy's organization.

As usual with these films, you can forget about anything grounded in reality.  When Paul Walker slams a guy two stories into a parked van so he can scream at the random thug, "Give me a name!" I'm pretty sure that's not how law enforcement works.  Even better is when Toretto and O'Conner have to illegally cross from Mexico into the US and they have to get past cameras with heat sensors and when they manage that, the border patrol sends in a helicopter.  While watching that scene, I'm pretty sure I heard Lou Dobbs get an erection.

But no one cares about that.  The film doesn't even care about that.  If they could just have cars racing each other interspersed with hot women grinding against each other for two hours and get away with it, that's what they would do.  Any time the film has to do drama, it does it with all the enthusiasm of a kid taking out the garbage.  It's as if director Justin Lin said "Cue the sad music, you actors do your best with these lines of dialogue scribbled on a napkin, I'll be grabbing some food over at the craft services table."

Lin cares (or at least should care) about the cars.  But I saw the film with folks who knew cars better than I and they noticed that certain parts were missing from the undercarriage since they're using stunt cars and not real cars. Why not CGI in the missing parts?  I can't help but wonder what intense car aficionados will think when they notice this lack of attention to detail.

But even for us laypeople who just like fast cars and big wrecks (without the grim reminders of car accident deaths), the film doesn't offer much.  There's a street race that's undermined by a laughable GPS system that I think was supposed to be a joke except Lin takes it so seriously at the beginning of the race that you start wondering when the usher will hand out the Xbox 360 controllers.  The film's big set piece of a chase through a tunnel isn't exciting at all and what should feel daring and impossible instead just feels cramped and repetitive since Lin has cut off most of his options by setting the scene in a confined space.

This is a shame because the film opens with a great sequence where we're not only reminded of why we liked Toretto in the first film, but also why this series became popular.  It's the right mix of editing, practical stunts, and CG and it delivers the excitement you're looking for.  Sadly, since it doesn't have much in the way of other set pieces or acting (and that's not to say that any of the leads are "bad actors"; they just have nothing to work with and are just struggling to work with the thread-bare character outlines they received in the first film), Lin just throws expensive cars and attractive women at you and hopes that your primal brain will just go "Money.  Tits.  Good." 

Because they haven't really tried anything new with this film, it remains as review-proof as ever since it offers the same elements to the same audience that lapped it up the first three times.  If you're a member of that audience, you're already strapped in and revving the engine.  For the rest of us, we'll just quietly retire to our Hybrid cars, turn on NPR, obey the speed limit, and spend our time and money elsewhere.