It was definitely bad. Tyrael becoming human was probably the single worst thing about Diablo 3. And the game mechanics really suck, so that says something.
Blizzard probably went "yeah, you guys like Tyrael? yeah, we got something good for him! We're going to make him a worthless loser! oh, and while we're at it, we're going to make angels and demons completely obsolete compared to humans! YEAH!"
What a way to piss on your own lore, by robbing the entire point of a game of it's value. Diablo was always about angels and demons, now it's about humans. Yeah, just like every other game.