So, I gave another try at Picasa after years. I only tested when it had just been released, and at the time I liked ACDSee much better.
Last version surely improved dramatically over the one I had once tried, as expected. It's a very nice piece of software, it's fast, nice and intelligent GUI, etc. So I just adopted once more as my main picture viewer. But this is all "normal" stuff.

There's one thing that just impressed me: face recognition. I mean, it is just scaringly effective. On a collection of 30,000 pictures, ranging from print scans, film scans, early digital compacts, to contemporary reflex ones, it is just finding faces and placing proper names on them. I can tell there's a lot of superb work in defining the recognition algorithm. It is by several orders of magnitude better than what I could ever expect such a small software could do. Tu tell you the truth, I still can't persuade myself that there in fact is some sort of biological signature still evident in a dark and low resolution picture of somebody's face when half covered by long hair, wearing a hat, and having beard, that makes it comparable to that same face shaved, short hair, no hat, in a bright sunny day.
And still, Picasa is getting it right almost always, whether it is sure of a match, or asks for confirmation, or suggests the proper names once you manually try to name a picture.
Of course, distance between the eyes, and the nose, and the mouth... Proportions of them... But to successfully get that piece of info! Wow. What a superb work they did.

Don't you too find that feature shockingly good?