There is some weirdness going on right now where you can actually mine minerals and gas with zerglings as Dehaka. They seem to harvest faster than drones. Looks like this was an ability they toyed with in development but didn't full remove the behavior correctly when they scraped the idea.
Overall Dehaka is outstandingly fun I feel. Even using his most basic boring army comp, his hero unit still provides tons of fun gameplay, plus you can move your production facilities forward throughout the map similar to Stukov. On top of that, he has a variety of fun alternate unit compositions that seem to be viable in different situations or maps and then there's his summons and his deep burrowing static defense worms to add more fun tactics to the mix.