Well! Trailer is finally out, as revealed by EqD in this post.

What can I say? My worst fears haven't been realised.  Firstly, and most importantly, the animators have gotten rid of the ridiculous anthro features that turned the girls into self-parodiacal bits of fan-art, far worse than most of the content on DeviantART.  Secondly, it looks like they've come up with a half-way decent set of plot devices and explanations for this.  Finally, it looks like we're going to get a replacement for Trixie as the character antagonist/anti-self for Twilight Sparkle in the form of Sunset Shimmer.

What I really like the look of is that this new antagonist could be a recurring character and maybe, just maybe, my long-suspected Anti-Elements group is beginning to take shape.  Additionally, the fact that the link between Equestria and pseudo-Earth seems to be permanent and the result of an artefact rather than a spell, means that EG could have a long-term impact on the show, including cameos and crossovers.

This isn't to say I'm going to be rushing out to see this film but I might get the DVD when it comes out.  It certainly seems to deserve the benefit of doubt and a look with unbiased eyes.

Just an additional point.  It could be a significant spoiler, so I'm going to put it in spoiler blackout: There is a male character who seems to become Twilight's love interest.  As all the characters we see seem to be humanised versions of ponies (including the CMCs), this could mean that there is a stallion in Equestria who is that character's equivalent.  So, and hold your breath shippers, there is a very real possibility that Season Four might have Twilight get a Special Somepony!