I have to admit, I'm blown away by Picasa. I did not realize I had "worked around" the fear that Aperture would screw up the database by having multiple Aperture libraries. I had about 6000 photos in my "managed" library, which meant every individual had been identified, every date was correct, and every photo was geotagged. I had several other libraries that recorded major efforts: like scanning my parents photos, scanning my in-laws slides and the like. In Picasa, they are all viewable in the library, albeit in different folders. I was kinda surprised to find I have more than 26,000 photos. I bought the program Gemini (MacPaw) to find duplicates and was stunned to find there were exactly 6.
I actually prefer the Picasa interface in three aspects. First, if you are looking at the thumbnails (like 20-30 on one screen), each thumbnail has a pointer on it if it is geotagged. There is a similar view in Aperture, but you have to select it. Second, if you double-click and enlarge the photo to working size, there is quite a bit of the exif data shown at the bottom of the screen, as well as where that particular photo is in the folder (example: 42 of 87). The faces approach (called People in Picasa) seems to be predicting accurately much more of the time then Aperture, but the interface is much better. Instead of showing all the squares around all the faces, with all the labels below, there is a pane on the right that shows the faces. When you hover over one of the assignments on the right-hand pane, the square appears on the photo. You can essentially do all the same stuff as Aperture.
I have not put any effort into photoediting with Picasa, as I am still adding the faces (1/3 done!). I suspect a different photoeditor will be needed to get the same capabilities as Aperture had. Likely will be Pixelmator.
Anyway, just a progress report.