Here's a bit on what I've learned about Lr from the
Adobe Press (edit) LR4 Class Room in a Book.
I bought LR4 (Camera Labs affiliate buy) a few months ago and recently installed the 4.1 update - Adobe lists it as a 750 Mb download - ended up at about 500 Mb on my disk, at no extra cost. 4.1 adds things like a Fuji x Pro 1 raw reader so I'm covered if I end up with the X Pro-1 (xP1?) in my bag

. Also bought Adobe Press LR4 Classroom in a book (Camera Labs affiliate buy too). The database capabilities taught in the book are sinking in. The LR database is essentially a photo data management tool set- like the ones used in my day job. I'm gaining an understanding of and, appreciation for the whole work flow subject. So far, the book and application have motivated my move away from a tried and true 'event/folder' photo storage and retrieval method to the Lr system. You can do all your file and folder manipulation in Lr so no need to go the the OS for these things. Picts are still stored on my hdd in folders but organized by LR in a logical and highly responsive (read fast- like instantaneous) catalog\collection structure. Once set up in LR, switching from travel to event picts to other picts taken years apart takes one mouse click. There is a stack feature for bracket, panorama, high speed action, etc. picts. Stacks help by compacting the visual content in various parts of the work flow. LR provides the user with the opportunity to apply keywords and meta-data to each pict or group of picts. These tags become the fuel for the powerful LR search engine. Adding keyword and meta-data to the picts on my hdd - 10 years worth - has been some work. The prospect of being able to retrieve very specific picts from all we've ever taken with a digital camera is intriguing. The Library half of the book has definitely changed the way my pics are managed- no looking back now.
But none of this is why I bought LR. I was after the Lr photo editing tools in the Develop Module. These tools are astonishing to me. So far I've relied on the LR video set at Adobe's site to learn things. They provide a good overview of the Develop module and, the others too. The book appears to cover the Develop Module in detail and I'm looking forward to working my way through it. As my photographic seeing and editing proficiency improve through this study and other texts, the temptation to over cook things will in time be replaced with a tendency toward subtlety and aesthetic quality.
It is interesting (startling really) to me, what can be dragged out of the Nikon P90 data by LRr. More to come as I go through the rest of it.
LR4 screen grab showing before and after appearance of a P90 pict.
Edit 120711
Done with the Book!
I am really liking LR. For the money, I can't get over what it can do. Never had any contact with PS Elements but I can't imagine it is this useful. Below is a composite of snaps assembled in the Print Module. Thanks for looking!
LR4 Print Module