I don't use iPhoto, but I did fire it up to see what's in it. I looked at it some years back and decided to keep using my camera software. I have an old Canon Digital Rebel XTi which came with software they call "EOS Utility". I download files into a "special" directory I set up.
The EOS Utility lets you download only the latest (since last download), all, or choose 1 or more specific photos. It also let's you set up a naming scheme. I have it set up to download and make folders (directories) for each day with the date as the name of the folder, and in it go each photo taken on that date with the photos also named by date. I like this method because it keeps every picture organized by date: e.g. 20110420_IMG_4258.JPG where 20110420 is the date the picture was taken and the 4258 is an incrementing by 1 number. The IMG is in every photo name so I can identify & search for pictures I know are from my camera.
Were I to use iPhoto I'd just import from the folder(s) I wanted indexed and stored in iPhoto.
As a "quick" test I just opened up iPhoto and chose my main Canon folder to Import. There are about 2900 pictures in that directory. They are large jpg files which are between 3MB and 10MB in size (I'm not into photos to the extent that I'm interested in RAW files). It took about 12 minutes to import all the pictures. Now in the Faces view (on the left in the sidebar) there is a ball spinning and the CPU is being hit pretty hard so it must be doing some sort of post-processing. I have no idea what the Faces view is all about.
I used Import from the iPhoto program menu. I don't know, but there may be a "Drag & Drop" way to import pictures.
Also, as a "Heads Up", if you're into photography there's a Photography Group here. It's not very active, but it's another aspect of the forum.
Photo Freaks
And of course there are "
User Albums" if you want to share any of your photos here.