Keep it - you paid for it and it does not need much space. Sometimes I am happy that I kept my iPhoto version for several reasons:
- Most important, it is the only way to browse two photo libraries at the same time, with only Aperture available you can only open on library at a time.
- Some older library items imported from iPhoto cannot be opened in Aperture, like Books and Cards.
- If you need to restore an older iPhoto Library from backup, that is not yet in the universal format, you cannot open it in Aperture and will need iPhoto to upgrade it first.
- If you ever have reason to suspect Aperture to be buggy you can open your library in iPhoto to check the library.
- And you cannot create cards and calendars in Aperture
- For compatibility reasons, if other family members use iPhoto ...
But TD is right, you don't really need it - I just like it
I am with Léonie on this. I have never used iPhoto so I actually deleted it a few OS versions back. Bad idea. iPhoto is so integrated with the ecosystem fully doing without it can create small "issues" from time to time.
And today with PhotoStream and cloud transfers I would for sure keep iPhoto viable.