I think Picasa is incredible.
The huge number of photographs and the even greater number of tags make it a bit difficult to work with. Hunting for a particular type of photograph is also a little labour intensive. However, the ability to share albums with friends and family could be a terrific help, given circumstances such as far-off relatives.
I will probably not continue to use this application. I recently bought a Mac and I'm excited at the prospect of starting to use Apple's photo organizing feature - I'm told that it is really terrific. Apart from that, I have some of the same concerns about Picasa that I had about Facebook - namely the "lifestyle" or "advertising" side of it.
On the other hand, I was pleased to see that it's possible to have access to your photographs limited to a particular set of people. I'm beginning to think that this might be an excellent way to share my "brownie" pictures with my daughter's brownie leader.