I tried LR/Aperture for awhile, but the latest version of iPhoto does pretty much everything I need, and feels a lot less "busy".
Busy.. that's exactly what my wife said about aperture, so I stick with the iPhoto for management. I like it. It does 'most' of what I need, but now with my DSLR I like to get in and really pull all the colors out I can with the pictures. I then 'export' at the highest jpg settings to iPhoto after I've tweak the images so the ones in iPhoto are the best (from my eyes) can be.
I like iPhoto, anything more would be Aperture 3 IMO. Combine the 2 would be nice, maybe have an "Enable Advance Editing Features" selection to enable the 'busy' pieces but leave the easy interface the default.
Some might say "the folder/album/etc is a nice organization" but for people like my wife who want it simple, quick, easy to use, iPhoto can't be beat. For people who want the ability to do more IMO Aperture is the way to go. For those who want even MORE detail, the Adobe products are pretty much the standard.
Myself, I'm the Aperture man. I like enough but not to much. I keep my management in iPhoto, my editing in Aperture, and I guess storage of master files until I need to prune them for space. But I do use both iPhoto for my main management and storage, and Aperture for my editing/secondary storage.