A friend of mine asked me why do I use Adobe Lightroom, when there is Adobe Bridge that ships with Photoshop, and has a lot of the same functionality. There are a lot of reasons why people use Lightroom. For me the biggest plus in Lightroom is portability. To understand this a little more I'll quickly go through my simple workflow.
After a photo shoot, I will import all my images into Lightroom. First I don't have to worry about file structure, because Lightroom does it for me. I can immediately add general keywords before the import and add my copyright information into the metadata of the photo. After the import is finished I stroll through the new images first by marking the really bad shots for deletion and the good and best shots with stars. They usually get 4 and 5 stars. Here comes the fun part. When I know I will be away from my main computer, for what ever reason, I will select all the 4 and 5 star photos from the shoot, and export them from the main Lightroom catalog, into another smaller catalog. Then I copy that catalog onto a portable hard drive, and I can edit these practically anywhere. I can edit them on my laptop, or even at my friends house using his Windows pc (I'm on a Mac myself). Did that Windows editing a couple of times when I was showing my friend a few tips I picked up, and I was doing this on my images. I keep working on that smaller catalog until all my edits are done. Even when I'm back on my main system and the edits are not finished I work from the portable hard drive.
So now all the edits are done, I just open the main Lightroom catalog on the main system, and import the smaller catalog from the portable hard drive into the main catalog. Lightroom gives me an option to overwrite existing files with the new edited ones, or just overwrite the metadata and editing options from the photos. Done.
To me this is one of the best features of Adobe Lightroom, and this is why I use it and will continue to use it.