It's pretty difficult to think of a more ridiculous way to start anything than with the image of a lawn gnome in a mankini -- it's kind of impressive, actually -- but what's more impressive is that what the trailer accomplishes with this joke is not humor, but rather to effectively ensure that the mankini, as a cultural in-joke, will never be funny again.
In other areas, the jokes mostly involve gnomes trying to be stealthy, but then -- LOL! -- they're totally not stealthy! About a quarter of the trailer's runtime is devoted to rehashing this joke in three different scenarios, which doesn't really bode well for the variety of the jokes in the film. Also, it FEATURES THE CLASSIC MUSIC OF ELTON JOHN, which is... We're not really sure what to make of that. Is it because Elton John kind of looks like a gnome? We're assuming so.
Really the only hope for this movie is if it is, as the trailer bills it, an actual adaptation of the Shakespeare play -- at least then you can be sure there'll never be a sequel.