I saw this movie on May 1st (opening weekend). This was the best movie in the series so far in my honest opinion. Vin Diesel, Paul Walker and Dwayne Johnson all in the same movie virtually guaranteed a pure action ride. As others have said you will want to stay for the credits (grr). Lastly, I convinced my girl who works late, late nights to see this at 10:40am. Not only are we guys eager to see this but the gals too; that makes for a Grade A Date Flick so don't miss your opportunity.
The first time I saw Avatar was at a cinema which offered the movie in a regular format, which I normally prefer. My movie experience was so enjoyable I just couldn't wait to see it again but in IMAX 3D. I wanted to see the added effect of the superior formats and it was well worth going again. Even if you're not a huge fan of 3D or don't feel IMAX is very special... it made the experience far better. Please don't let the opportunity to see this movie in IMAX 3D pass you by!
***Side note*** At the end of the movie, both times, the entire audience applauded & the vast majority stayed through the entire credits! That in and of itself as a fact is a groundbreaking spectacle, especially if you've seen a number of movies in theaters.