I love iPhoto because, like burreyeann said, it’s so easy to use.
But that’s not all. You should have included an “iPhoto and Aperture” option. Here’s why.
I transfer every shoot into iPhoto. Jobs with a professional purpose/objective are consequently imported into Aperture.
My iPhoto library is backed up to one external hard drive (a Maxtor 320GB USB) and the Aperture vault is assigned to another external drive (a La Cie Firewire 800 250GB drive) - which means my workflow begins with a quick ‘sort and sift’ in iPhoto, is refined where necessary in Aperture, and both libraries are backed up, with pro shoots backed up twice for good measure, with next to no extra effort. When the external drives fill up, (only the La Cie has, so far) I know it’s time to archive old jobs to optical media to free up drive space.
The new iPhoto will make this workflow even more attractive.
I have looked at PC-based management solutions and the only one that appeals is Lightroom, which I could use on my Mac anyway, so why bother?