This is Aperture 3? A3 is very good. Most importantly to me, it allows you to use plug-ins for editing which iPhoto doesn't really do well. I use all of Nik's stuff as a plug-in to Aperture 3. You can the basic editing with A3 but it can't do Photoshop or Gimp stuff if you plan to swap out skies, remove elements from a picture, change backgrounds, etc... I do all of my basic editing in A3 w/Nik Plug-ins and then use Gimp (still too cheap to buy CS5 although I did recently do a 30 day trial) if I need more drastic editing!
A3 will allow you to easily:
- touch up portraits (clone, blur, etc...)
- darken skies (using brush tools)
- selectively sharpen, soften, etc...