IMO, LR isn't 'good'. It's a great program
The catalog function in LR is miles ahead of the catalog function in PSE. LR does, however, demand a change in the way you 'think' PP. In LR, you don't change the original file, it's kept intact. So, when you're going to use the photo for something (from posting on the web, via displaying on a TV or computer screen, to making large prints), you generate a (throwaway) JPEG from the processing instructions in the LR catalog file and use that JPEG copy.
Not really. Adobe uses the same engine in all the Photoshop products, be they PS, PSE or LR. So, anything you can do in PS or PSE (except layers and heavy retouch), you can do just as well in LR. I use LR for PP of both raw files and JPEGs, and I don't see that I get inferior results by PP'ing my JPEGs in LR compared to doing it in PS. And it's a lot easier in LR