Having not been able to use Picasa for Mac due to its incredible high amount of CPU usage in earlier versions seems that with version 3.5.x the Picasa team finally did their home work pretty well:

Now Picasa for Mac is great app to find and manage images on your hard drive without the need of organizing them in specific folders before or link the to iPhoto.

While the new face recognition feature needs some time to find and index faces in thousands of images the results really impressed me.

Finally well done, Picasa team!

One important hint regarding your data protection: Think twice if you want to use Picasa with an online connection - especially if you try to import the name tags of your existing Picasa online account !

If you do it, Picasa imports ALL addresses from your Google online address book too without asking - and if you want to tag your images in your local Picasa for Mac app later, it always tries to connect the pictures with the real name, email address, phone number etc. of your Google address book entries.

That's definitely not what I like - especially since Picasa for Mac doesn't allow you to delete those imported addresses from your Google online address book later in a batch mode, so you would have to work on every single one - for me nearly 2.000 entries. Be prepared !