Tactical
These guys benefit from the fact that they can take a mixture of ranged and close combat weaponry. Don't take them as purely close combat terminators with thunder hammers (you're not taking lightning claws, right?), you have Deathwing Knights for that, instead, take 1 in 3 as a Thunderhammer wielding Storm Shield. Add an assault cannon for mid-field duties or a cyclone missile launcher for back-field objective sitting.
(4 with storm bolters, sarge with power weapon, 3 power fists, 1 thunderhammer/storm shield + cyclone: 250p)
Troops
Better yet, take Belial or Azrael and field these guys as Troops. Plonk a squad on every objective in your deployment zone and watch your opponent squirm. Remember, these guys have split fire, so you can shoot the Cyclone at a vehicle while unloading the Storm Bolters on some infantry.
(Belial, 2x Tactical Terminator squad: 690p)
Deathwing Assault Bomb
Take Belial and a squad of 10 Terminators. Get 3 thunder hammer/storm shield guys for protection against low AP weapons. Add in 2 assault cannons.
Use Deathwing Assault and Belial's Tactical Precision rule to deep strike where needed most. Obliterate something with Vengeful Strike rerolls the turn you drop in.
Subsequent turns, you can use the split fire rule to shoot one storm bolter at the target you want to assault and point a barrage of storm bolter and assault cannon fire in the direction of another. Bloodbath guaranteed!
(Belial + 10 terminators, 2 assault cannons, 3 TH/SS: 685p)
Conclusion
Last couple of battles, I took the Deathwing Assault bomb (with squad sizes ranging from 6 to 10) and they haven't failed me yet. I really like the raw hitting and staying power of this unit. It is however a bit of an "eggs in one basket" thing in battles of 1500 points.
How do you use your Deathwing dudes?