Apple's Faces are just a fancy tag. Which LR does really well. Just because Adobe doesn't throw a box around someone's face doesn't mean I can't tell who's in the photo. It's just another feature "fluff" instead of adding real features.
With respect, I disagree with this statement. I think... if Aperture's Faces is the same as iPhoto's Faces then it is way more than just a box around a face. Faces uses facial recognition technology to go hunting for faces in photos you have not yet tagged and compares them to faces you have already tagged. Once you have tagged and corrected a few faces it can be frighteningly accurate. In iPhoto Faces has found and identified a couple of relatives in framed pictures on the wall in the background in a couple of shots I had. And Lr has nothing like it.
I agree that generally speaking, if you are working with current images, it is just as easy to identify and tag people as you import. And at that point the Lr tag is the same as the Faces tag. But Lr doesn't have the Facial Recognition ability to search all your images for faces it knows.
In one project I did I scooped a couple thousand photos of my young relatives from their FaceBook pages. Of course I had created Folders for each "victim's" account, but even then there was a lot of overlap of the relatives into each other's FB pages. Once I had them all imported into iPhoto, and tagged by FB account I then let the Faces technology loose on the collection and quickly added all the face tags for the relatives who appeared in photos from multiple FB. At the last minute I needed to find all the photos where a non-relative appeared. Because I hadn't tagged them on import, I simply asked Faces to find all instances of that face.. and it worked really well. Within a couple of days I had every face that appeared in everyone of those couple thousand photos tagged with a name or an "Unknown".
With that said, once I had them tagged in iPhoto I then imported specific sets into Lightroom to work with since that is my application of choice. But... don't dismiss Faces...it is much more than just a tag.
All of this is assuming that Faces in Aperture is the same as Faces in iPhoto.
I keep iPhoto specifically for a couple of features that Lightroom does not have.... Faces is one of them.