So let's get this out of the way. I like the concept behind them; having Pokemon based on Fuujin (Tornadus), Raijin (Thundurus) and Inari (Landorus) is rather neat and Tornadus being the only pure Flying type for quite some time made him unique.
But aside from that, I'm not a fan and I'm kind of tired of them to be honest. The Incarnate forms are a bit too similar to me and their designs don't appeal to me very much and the Therian forms (I like this name because I know what it means; it's another word for beast), while doing a better job making them different, still look really weird for my liking, Landorus especially.
When it came to the competitive scene, I'm aware that these were some of the best Pokemon in the game, but I don't like Pokemon based on how good they are competitively. But I like to watch people battle from time to time and now I'm sick to death of seeing Landorus Therian for the umpteenth time that now every time I see him, I'm like "ugh, this thing again" even when it's not a battle. Yes, they're very good Pokemon, but seeing them over and over is tiresome.