I came from Aperture, but I LOVE Lightroom. You get a small collection of the more common adjustments from Photoshop, plus a really nice cataloging, keywording, and organization application. I'm not as sold on the Panel-based workflow, but it's not completely obtrusive. Flickr uploading works well, and it keeps comments, locations, metadata, etc. in sync between your local copies and Flickr, which is great for me.
What I really like is that, unlike Photoshop, all Lightroom edits are non-destructive. I've come back the next day and not like something I changed, and can easily tweak my prior work until satisfied. That's excellent. Or create virtual copies (without storing the image multiple times) and tweak several different ways.
I know you're looking at Lightroom from the App Store, but download the trial and give it a test run before you buy.
https://creative.adobe.com/products/download/lightroom
Alternatively, watch these tutorial videos with Julieanne. They're fantastic:
http://tv.adobe.com/show/learn-lightroom-5/