Geomancy is a two turn move. On the first turn, you charge the move's power, so no stat changes happen in the first turn. However, all normal moves that would hit you that turn do hit you, unlike Fly and Shadow Force. On the second turn, you gain +2 special attack, +2 special defense, and +2 speed.
So yes, Geomancy is only similar to Wish, because it doesn't dodge certain moves when in the middle of using it. Source.
Edit: Yeah, it is like Solar Beam except that it doesn't do damage. It only changes stats.