Picasa is a terrific software to organize pictures. Its unbelievably simple to use and can handle a million pictures with ease. With the recent update on Picasa, organising my pictures has just gotten easier.
But let me specifically review 2 features: Name-tagging and geo-tagging, 2 features that I use quite extensively in picasa.
Name Tagging: This was an exciting feature, in fact when it was lauched in the Picasa Web Albums last year (https://googlephotos.blogspot.com/2008/09/announcing-picasa-30-and-new-version-of.html) I was really surprised how picasa web albums could recognize faces from all over the web albums uploaded and quite accurately group pictures together. Exactly after a year, this feature has been ported on the desktop application. And it works fine, except that it does not group pictures together.
For example: if I were to name tag on Picasa Web Albums, I could easily tag 200 faces in less than 10 mins (approx 6 mins) if I were working on a moderately fast Internet connection. However, with the desktop name tagging, grouping of pictures is limited to less than 2 pictures, therefore it takes a lot of time to name tag - 200 pictures would probably take 20 mins or more. So I feel the intelligence programmed into the desktop application isnt as exciting as the one online - therefore I would stick to using the name tagging feature provided online.
Geo-Tagging: Geo-tagging on the other hand has made things really fast. Previously I would have to use Google earth, which could get really slow. However with the geotagging facility embedded into Picasa, its lightweight and does not require too much system resources - its like how you use the maps.google.com except that it is embedded into Picasa so you can geo-tag with ease.
Some other features I really like about picasa in general is its ability to be extended - like I can place a button to upload to facebook+flickr with ease. Just download the plugin and it works like a charm.
You can see how much ive used picasa by logging into my web albums link: https://picasaweb.google.com/savioseb/