I recently switched from Picasa to iPhoto. There are many things iPhoto does well:
- iPhoto supports Smart Albums, which show you all photos that match one or more rules you define. I have a Smart Album for each of your cameras, one for long exposures, and so on. Most forms of organization, whether folders on the filesystem or labels in Gmail, require manual management — you have to put things that belong to that category in that folder or assign it that label, and if you accidentally label something wrong, your organization is now inaccurate. Smart Albums don't suffer from any of these flaws — they are always up-to-date, and they don't make mistakes.
- In addition to Smart Albums, iPhoto also supports plain Albums, which you manage yourself by adding photos to and removing photos from them. These are still more flexible than folders on the filesystem, since a single photo can belong to multiple Albums.
- If you have a photo in which the highlights are clipped, that is a photo where some parts are too bright, iPhoto lets you fix this. Picasa doesn't — it only lets you further increase the brightness of these regions, which makes no sense.
Picasa is marred by bugs — the app doesn't reflect newly added photos, removed photos continue to show in Picasa, it hasn't been updated for the Retina display, it sometimes shows the title bar in full-screen mode, and the whole UI theme is awkward and not Mac-like.
In fact, Picasa seems to be abandonware. Other than adding new buttons to share to Google+, there have been nothing new in years.
It's time to jump ship.