I actually wrote up a document, based primarily on copying the "how to play" section in the official 4E module "Keep on the Shadowfell", which I titled "Learn how to play D&D in 8 pages of 12-point font". The majority of it is copied directly, but I did add a few things which I felt were too important not to have new players (or new DM's) glance at before playing.
They read like boardgame rules -- dense, but clean. It is all there, but without much fluff. (unless the original WotC document included some fluff)
I e-mailed it to my friends, who are complete newbies to D&D, and had them read through it. After reading it a few times, they know enough to play. If they have it memorized, they probably won't have to crack a book unless they do something out of the ordinary or odd.
I'd be willing to send you the document, if you want to read it, and that should get you up to speed on 4E.
////////////
The main points --
- a combat grid is required, but whatever representation you use is up to you (miniatures, wooden discs with erase-able surface, printed cardboard standup miniatures, etc.)
- You get 3 actions a turn, in any order -- a standard action, a move action, and a minor action. You can give up your standard action for a move or a minor, and you can give up your move for a minor.
- you get 3 types of powers -- "at will " (use whenever you need them), "encounter" (use once an encounter), and "daily"(use once a day). The most useful tool I've seen is to use "Power Cards" and have these powers printed off on the cards with erase-able calcations pre-figured, and all information for a power written out (saving you all sorts of time in calculation, or looking up rules). These simplify book-keeping, speed up play, and keep things organized.
- Combat encounters are larger (often encompassing areas larger than one room, and even more than one "group" of monsters) and thus take a little longer. The game is also more tactical, and thus players can get trapped in "Analysis Paralysis" if they're not used to tactical miniatures games.
- Your default melee attack, and a lot of your old-school defaults, are things of the past. In a way, a new player is actually going to have an easier time of it, because they're not going to make certain assumptions about the way things work.
As for the "Living Forgotten Realms" document (which I assume is what you're referring to by LFR) it is a straight-up add-on to the basic 4E system, giving you minor bonus material you can insert depending on your starting city, etc. It also gives you enough information to start a (basic) version of a new class (the swordmage) and a new species. It is a completely playable document, and is as useable as anything in the basic books.
I've found the system remarkably clean, straightforward, and intriguing. I gave up on D&D years ago in favour of other systems, but this system intrigued me enough to get me excited, and even got my wife excited.