It might depend on how it's handled here compared to X/Y. In the latter game, hordes were terrible because they included Pokemon with the most obnoxious movesets and/or abilities possible. They were also introduced way too early in the game, and I found it sickeningly hilarious that the game recommends using moves that hit multiple targets to deal with hordes, yet such moves aren't truly available to you at the time when they are introduced. When you also have single higher-leveled Pokemon that gives way more experience than any horde battle, coupled with the fact that they appear among random encounters, instead of being isolated from the normal encounters (Did they learn anything from B/W?), makes hordes one of the most obnoxious waste of time in the main game.
I'm worried that OR/AS is heading in the same direction, and it's making me shudder in fear.