Yes. It's a pedal based PM but unlike the normal Garmin Vector in which both pedals sense force, the S version uses only the left pedal to calculate power, similar in that respect to the Stages PM. The two-sided Vector is legit and from what I've read the Vector S is as legit as any singled sided PM.

Here's some info, though it's not review: Garmin announces Vector S: $899 power meter, also announces Cycling Dynamics | DC Rainmaker