It does not have face recognition. It also lacks decent GeoTagging support - it can list the coordinates and send you to Google Maps in a web page but that's it - no editing coordinates, no built-in mapping, etc. I would find this more valuable than faces, but these two options are two of my most wanted "non-essential" items.

I can't say I use it as a photo "viewer" unless I know I want to go and work on a specific photo or find a photo. That is to say, I use a number of other programs to quickly look at images of all kinds on a daily basis, however I use lightroom to manage my digital photo library. SO when I'm looking for something or I want to show someone a number of shots, in those cases, I suppose I do use it as my viewer.

Photo collections and photo files are getting bigger all the time, that said, make sure you have a system with decent specs to run Lightroom. I don't find it especially quick on my 2.9GHz Core2Duo MacBook Pro.