I kind of don't like how random they've been with Zack. Like, he was a total weasel when he was Kaito's underling, but he gets a Lockseed and is all of a sudden the only hero in the show aside from Kouta? There's no real reason other than "Geez, I guess more than one of our 200 Riders in this show should be kind of good." It didn't seem to me like they planned to do anything with Zack, so they just pulled it out of their arse.
Also: even though it's ridiculous to have a walnut Rider, I can't take Knuckle seriously when he's armed with Sock'em Boppers.