As far as how the image handling feels inside the applications: When I was trying Lightroom, its photo management felt very much like Adobe Bridge to me. Some people will like that because they are familiar with it; but I never really liked Bridge.
I've used Bridge for batch renames of files ... worked fairly well, although my SP 1.8GHz G5 PowerMac is getting stressed.
Really, though, to beat on the same drum as my other post - trial versions of both are free, so the best solution is to check both out for yourself.
Took that advice yesterday, although didn't get through all of the Aperture checks on the iPhoto import option ... with 10,000 images in my library, its saying that its going to take 4-5 hours (currencly says its working on roll 93 of 189 ... 3 hours to go).
-hh