I have been using Aperture 3 for the past couple of weeks trying to become more comfortable with the interface. I updated to 3.0.1. It seems a bit more stable and a bit faster, but still not fast enough.
I did a test with five images from a wedding that I photographed last year. I edited the images with Lightroom and then did the same adjustments in Aperture. It took 12 minutes in Lightroom and 15 minutes in Aperture ... 25% more time. Some of that has to do with me being more comfortable with Lightroom, though I did practice in Aperture quite a bit to minimize that. I made videos of the two tests, you can click here to see them:
I did get a chance to explore a couple of areas of Aperture that I didn't get to in my initial review.
Image quality - Aperture 3 image quality, IMO, is better than Lightroom, not a huge difference, but noticable. 95% of my photographs have people in them so skin tones are important. I found Aperture's skin tones to be more natural. This is somewhat subjective and the people at Adobe may think that their conversions are more natural. Of course you can always adjust Lightroom to correct for this, but out of the box Aperture just seemed more natural to me. I did try all of the color profiles for Lightroom, but I just couldn't get one that seemed as natural as Aperture. The color and noise characteristics for higher ISO images is superior in Aperture. For high ISO images you can get very grainy and patchy spots in Lightroom, where Aperture images seemed to be smother and cleaner without loosing detail.
Metadata - I have started to become more diligent about updating image metadata so I was interested to see how Aperture 3 handled this. There are about 10 fields that I really care to keep updated. In Lightroom I found that I was jumping from panel to panel or scrolling up and down to get to those fields. Aperture 3 allows you to set a preset so that you can view only the fields you want to see. This was nice. The customizable keyword buttons were also very easy to use in Aperture 3.
Cropping - It appears as though 3.0.1 defaults to an unconstrained crop tool. This is great.
SPEED - This is the main area that I believe keeps Aperture behind Lightroom. It just can't keep up with my editing. I find myself constantly waiting for Aperture to catch up. The "processing" wheel comes on far to often. I want to see the results immediately when I make an adjustment. Waiting 1 to up to 7 seconds for changes to appear on the screen is just too long for me. I shoot with a 12.3mp Nikon D3 so these files aren't that big by today's standards. I would assume that bigger files would make this problem even worse.
Tehter Support - As I mentioned before, Lightroom doesn't have this feature. One thing that the tether feature does on my Nikon D3 is that it allows the D3 to put a copy of the photo on the CF card as well as a copy on the hard drive of the computer. I understand that the D3s supports this feature, but the D3 and D700 do not. The one bad thing that I found is that if you take out the USB cord from the camera and put it back into the camera Aperture downloads all the images from the camera to the computer, even the ones that it downloaded when you were tethered.... oops ... you end up with a lot of duplicates. But there is a nice piece of mind when I am shooting tethered to know that the images are being saved on my CF card and the laptop.
A lot of people use Aperture for its DAM features. Being able to view projects visually is very attractive and useful. Lightroom just gives you a list of folder names and collections. The ability to group albums, slideshows, books, etc. by project is also helpful when it comes to keeping things organized. Aperture allows you to include video in your asset management is also a big plus over Lightroom. And of course, the ability to tag and group photos with face recognition and GPS location is something that could be useful. I personally have a separate Lightroom library for each client project and then I import the libraries into a master Lightroom library when I am finished with the job. One thing that I like about Lightroom is the ability to easily search on any metadata field such as lens, camera, ISO, location, etc. You can do it in Aperture but it wasn't as easy or intuitive.
If Apple could fix the performance problems that I encountered I would probably switch from Lightroom. When I make a brush stroke or change an adjustment slider I want to see that change immediately. It is not just about being impatient, it is about the fact that you are never sure that the change you made is what you were looking for and when you see nothing happening on the screen you continue to make changes and then when the visual does materialize you realize you over did it and have to go back and undo it to some extent.
The clone and retouch brush must be redisgned to allow you to go back to your initial adjustments without deleting the ones that came after it. And when I paint a mask with an adjustment brush allow me to use that same mask with another adjustment brush. This may actually help their performance problems a little bit because the application wouldn't have to recalculate the mask for very adjustment parameter.
Bottom line is that Apple / Aperture has made big strides with this release and has made themselves a serious competitor to Lightroom.