I spent a good part of my weekend getting comfortable with Aperture 2.0. I've been using Aperture for about a year. I'd like to say my choice of Aperture was the result of long testing and analysis between Adobe Lightroom and Aperture but in the end it came down to a very good deal when CompUSA was going out of business and the knowledge that an Apple product would inherently integrate better with OS X (which it does).
I really didn't have much problem with version 1.5 and found it quite useful. That being said, 2.0 is a significant improvement.
Aperture has always been good for organizing your library. I really like that they put some of iPhoto's innovations in to the new version. Particularly image scrubbing and .mac web galleries. I have roughly 8,000 photos in my library and it is very easy to find and work with all of them using Aperture.
Not only is the user interface easier to grok, there are some new tools that are fantastic. I particularly like the sliders for recovery (blown out highlights) and black point (too dark darks). Likewise the new vibrancy slider is a really nice tool for giving an image pop without screwing too much else up. Another tool I'm starting to experiment with but a little intimidated by is the dropper on the Color menu which allows me to adjust a specific skin tone.
So does Aperture replace Photoshop? No. However, if you do a decent job at the time of image capture, Aperture will be all you need for alot (if not most) of your images. All of the pictures in this article were only corrected in Aperture.
I'll write more on Aperture once I get a bit deeper. For the time being, if you are considering Aperture, I recommend you go watch Apple's very good tutorials right here. Any other Aperture jockeys out there? If so write in or comment.