3D has become ubiquitous for most blockbusters, and next month’s Star Wars: The Force Awakens is no exception. Between 2D and 3D, 70MM IMAX and standard, there are a multitude of different ways to be able to experience the movie.
source: Cinema Blend
So there are three versions of the new Star Wars movie: 2D, standard 3D, and 70MM IMAX 3D
According to slashfilm.com, Director J.J. Abrams only shot one sequence in The Force Awakens on 70mm IMAX film stock, the rest was shot on 35mm film, and in an interview he claimed
When I was watching the reels in 3D, there were a number of shots — and I know this sounds insane — that I hadn’t understood in the three-dimensional space quite the way I did when I saw them in 3D. I actually felt that there were things that were playing better in 3D. I had never felt that before. And if people have access to a theater that has laser projection, it is shockingly better.
The following images illustrate the differences between the normal 3D format and the IMAX 70MM.
The website Tech Insider recommends fans to watch the 3D version, but only if the movie theater accommodates the 70MM IMAX version
Unless you're seeing this on a true IMAX screen and in 70mm (one of these theaters), go with the 2D tickets.
Wikipedia informs that the film was released in N. America on December 18, 2015 in 4,134 theatres of which....
... 3,300 were 3D locations, a record 392 IMAX screens (13 of which are 70mm), 451 premium large format screens, 146 D-Box locations, as well as releasing in the Dolby Vision format (High dynamic range, Rec. 2020 color) in Dolby Cinema. Worldwide, it will be released across 940 IMAX theaters, a new record. On December 18, 2015, the film began playing on every IMAX screen in North America for four straight weeks up to January 14, 2016.