I'm a huge Tolkien fan, and have read all the lore I could possibly get my hands on. I love how Azog's character, especially in the movies, has been transformed from a fearsome Orc leader in the appendices to a full-blown, complex antagonist. The pale, almost ghostly depiction in the Hobbit trilogy is chilling, and it sets him apart from the regular Orcs. But I am aware that he wasn't actually alive during the battle of five armies, so the movies added that bit, which in my opinion, kind of betrayed Tolkien's lore.
Still, there are some redeemable qualities that the movies bring out. In the books, he's just this brutal enemy, but the films give him this whole backstory, this burning obsession with wiping out the Dwarves and reclaiming Moria. It makes him a much more compelling villain, someone you can't help but be intrigued by, even as you root for his downfall.
Sure, the movies take liberties with the source material – his whole rivalry with Thorin is a big change – but I think it adds another layer of depth to the story. It gives the Dwarves a personal stake in defeating him, makes their victory that much sweeter. Lots of LOTR fans have different opinions which you can read about below. Later, check out these Dungeons and Dragons players who experimented with house rules… that totally backfired.