Before B2/W2, I thought it was a silly thing. It wasn't really important, it looked odd, and it was just there. When the sequel hit and we got the fusions, it became fucking awesome. Much like Giratina, it got fleshed out enough to make it stand out as its own thing, despite relying on accompanying legendaries to draw its power from.
The stubby tail is a nice touch, as are the mismatched wings and horns. The asymmetrical design really lets it stand out as something unique. I expected it to be voiced by a grumpy old man, and I wasn't disappointed.
