What I like in picasa
It's been now many year I have been using picasa, and I still love it.

I love its simplicity of use, and the fact, as nearly always with google, that it's simply good for the really useful features. 
Along the years, I have been using it to manage more than 10000 pictures, with 3 different OS, 5 different PCs, and I never lost anything, especially time on complicated installation or upgrades. It's still agile despite this fair number of pictures.
Now, it also brings new and useful features :
- Picasa face recognition is very impressive. First, its ability to find faces (you sometimes end up with a face detected on a picture in the picture !), but also  its accuracy. For example, picasa is good at detecting children faces from baby through every very changing steps of its growth.

- Map's location : great especially when used with already geo-taged pictures.
- Tag's.
These three features combined are a great way to add information to your collection, without spending hours. 
Other features are easy ways to share with your pictures with your friends :

    - The integration with Picasa web albums 
    - The Flick upload plugin
    - Create a movie presentation


What could make picasa even better :

 - batch tasks

- ability to fully edit IPTC

- raw conversion and editing

- google apps integration

No doubt picasa will continue its maturation, and keep at a good distance all the complicated and far too expensive softwares that claim to be the clue to organizing photo collections.