Yeah I was actually happy with this guy. Why? Because he is by far the most competent and dangerous of the villains. He wasn't play for laugh and he was darker compare to jealous goddess, Q, and a queen that was trying to find food for her people. While Discord and Nightmare Moon mostly spend their time trying to stop the Mane 6, Sombra already did with out even being there by setting traps or hiding clues before his imprisonment (this is what we call "The Chessmaster" or "Dangerously Genre Savvy"). Also he almost won! The only reason he lost is because Spike decided to go with Twilight. If he hadn't been there to snap her out, Twilight would have been stuck in her nightmare...... should some one make a fan fic about that?..... anyways yeah I liked King Sombrero.
And even the lack of backstory makes him scarier..... ok some information would have been nice.... and a little more dialogue.
Also like some one in EQD said. Nightmare Moon has the best back story, Discord has the personality, Chrysalis has the motivation, and Sombra has the best presence.
Also because I treated him more as a plot device while I was watching the episode.