i found this mission pretty easy. if you can wait to get the kill and stay a little bit behind her to scope out the target then its all good and should be able to get it in one attempt.
wasn't too difficult but wasn't easy either and as sky said took a bit of patience and on the 3rd attempt i did finally clear. what i did find annoyingly difficult was destroying Leo's 4th war machine.
[Edited by saurabhfzd, 4/8/2011 5:25:25 AM]