First thing to note is that they are unreliable repeaters when used with the smartthings hub, so you can Bork your entire zigbee mesh. 
for this reason among others the only official integration method is to use them with the bridge.
As far as a specific feature, when used with the bridge you can specify their power restore feature at either the bulb or the room level, which is pretty cool. It means you get to pick which bulbs will turn on bright if power is cut and then restored and which will retain their previous setting.
See the community FAQ for more details:
FAQ: Do I need the Hue Bridge to Use a Hue Bulb with SmartThings?