First, and foremost you have nothing to fear. There will be NO SPOILERS in this review. Until 3-4 hours ago I was hiding under a rock in fear of spoilers just like you. I won't be spoiling a thing. I may post a spoiler review elsewhere for those interested in seeking it out. Finally, I DID see it in traditional IMAX the way it absolutely should be seen.
The movie is fantastic to say the least. Anne and Hardy stole the show. I had no trouble understanding lines. Bat-voice was better than in TDK. Lots of really great and unexpected callbacks to the previous films. Im surprised reviewers complained about the second act/halfway point because it contained some of my favorite scenes (though the climax/third act is in a league of its own!) The predictability/unpredictability will vary from reviewer to reviewer. I had a strong suspicion how certain things in the ending would go, but I was surprised by others. The phrase full circle is thrown around a lot and it definitely applies, because the film is the absolute perfect bookend to the trilogy. I have some minor gripes (most are too spoilery to post here, I'm afraid) but as I was leaving the theater I got in my car and as I was navigating home I pulled on to a small side-street that just so happened to be named "Shumacher Lane". That puts perspective on things.
As far as Oscars, Id say chances are low. Its just not an Oscar film (and it wasnt ever meant to be). Maybe some of the smaller awards but not Best Pic in all likeliness. Ill answer any other non-spoilery questions that I can, but I probably wont get to them until tomorrow.