So harlies don't technically have 'fly' but they can advance and charge , move over terrain like it does exist, fall back from combat and charge again and they can jump over you units. All there weapons are high ap in close combat and they have lots of melta equivalent weapons . They ride in flimsy transports with a -1 to hit and a 4++ , apart from that they have jet bikes which are epic in combat ( and can assault flyers ) . And the solitaire moves a crazy distance and hits very hard in assault. Expect turn 1 charges and hope you have lots of tightly placed bubble rap. If you survive their charge then they are out of there transports and they die like toughness 3 models should :-)