Lightroom is my new favorite software. It's not perfect, and on occasion can be downright frustrating, but it also saves me hours of work, which has in turn encouraged me to be a bit more aggressive in my retouching choices.
The best way to explain why it's so helpful is by running you through my work flow. I come home after a day of shooting cat photos at a shelter, pop my SD card into my laptop, and allow Lightroom's downloader to do its stuff. I have a keyword and metadata preset that it automatically applies to each photo, and all I have to change is the name of the directory in which to drop the photos. I shoot simultaneous raw and JPEG; Lightroom loads the raw versions and just copies the JPEG files.
Once downloaded, I scroll through the photos, adding the ones that have potential to a Quick Collection by pressing "B." I frequently have frames for which the flash didn't fire, so as I scroll through, I hit Auto Tone to bring up the exposure and see if these black photos are salvageable. After sorting through all those images, I then filter it to the Quick Collection for further work. For each of the photos, I need to decide whether it's going to my Web site, Petfinder, or both. I make a pass through the photos, retouching for tonality and cropping for aesthetics; this usually takes about two minutes per photo. I then export to one directory using my high-resolution JPEG preset. While that's processing, I go back through the collection, drop out the ones I don't need for Petfinder, then recrop the remainder for best animal presentation. These get exported using another preset, which compresses them and constrains the maximum image dimension to 500 pixels, and drops them in a second directory.
This is both a typical and an atypical work flow--one of Lightroom's charms is you can adapt it to many different processes and can move back and forth almost seamlessly between tasks. There's nothing really new you can do with Lightroom--Adobe Camera Raw has had this sort of nondestructive editing capability for a while--but with Lightroom, it finally feels natural to not worry about saving versions. There are shortcut keys for everything, and you rarely need to go to the menus. Property panels slide in and out to maximize screen real estate.