I have been playing DF since ptr and no he is not a hard hero, a different style of hero yes but not very hard to play. His difficulty level comes from the fact he doesn't really fit into ow too well for his abilities and some heroes really hard counter him and shut him down more then any other hero. He is hard to play in over 50% of all match ups (map and team comps of both teams) so when he does find his spot in a game he can be very very effective and even seem op in some situations.
some simple DF tips to play better is to start a fight with a Seismic slam but as you leap 180 behind target/s then learn how to uppercut and shoot your target at the same time (also mix your melee into close combat situations to extend your small ammo clip).
Rocket punch has it's obvious escape potential as well as the one shot mechanic on walls so if no wall no punch to kill (unless low hp that just a tap will kill them, and also utilise the damage from a small tapped punch to out position targets while still doing damage).
His ult is ok for kills and best used to escape inc damage (or move to high ground like Chipsa) but always look at ult % as it can be a great mix into a combo to refresh abilities to get more kills after you land.
