I am pretty sure that most people that frequent this site, know that I moonlight as a photographer. My workflow pipeline used to flow through a series of Adobe products, and when I made my transition to Apple, I also picked up their professional photo software. The majority of my time sorting, rating and adjusting photos is now done using Aperture, with only the really serious editing falling through to Photoshop. It only made sense, when the newest version of Aperture came out, that I would upgrade.
Usually upgrading Apple's software is a breeze, Aperture is the exception to the rule.
The software installed just fine, and at first appeared to be working wonderfully, but then some of the frayed edges started to show. At first, it was the new Faces feature they include. The computer spent about 8 hours scanning my entire library for faces, and then one is supposed to go and put names on all the faces. The problem was the majority of the images presented to me were just black. I went through skipping the black images, thinking that the software was confused, when I came across a straight black image, and Aperture was asking me to confirm that it was somebody. At that point I knew something was up, what I didn't know was how deep the rabbit hole went.
The support forum recommended I perform an 'Update Previews' which took my computer under an hour for the 35k + images in the library. After that was completed, I still saw the black images in the Faces section of the application. At this point my business partner recommended I try rebuilding the database; I sent Aperture on its way and it methodically rebuilt the core of the library. When it was done, I nearly died.
I navigated to the browser, and was presented with a checkboard of 'unsupported file' exclamation points. Panic subsided when I remembered that I had the v2.1 library backed up (twice), and that I could restore anything that was screwed up now. Back to the support forums, and I found a gentleman who encountered the same problem (also shooting Nikon), and found that the magical 'Reprocess Masters...' menu option was able to correct his problem. I sent my computer about this task, and about 2 hours later, I can see my library.
Although, the blackout images in Faces remain. For now I'm not going to try and fix that problem. Take it from this early adopter: Wait for a few more releases before jumping to version 3.