I've been playing some Lissandra and i've been doing quite well with her. She's tricky to play at first and you have to be in a mindset that you won't get a ton of kills, instead you'll get a lot of assists. She's kind of like Twisted Fate, you don't really ever want to 1v1 with her since you'll lose a straight up fight unless you did a lot of harrass and the enemy is stupid enough to stick around with 200 HP. However, you'll never die since Lissandra can't be touched by any gank. Getting ganked? Throw your E to someplace safe and walk in another safe direction, no matter what you do you'll always be safe.
The only thing about Lissandra is, is that she's quite squishy and she needs to get in close to do damage. Don't expect to 100-0 an enemy by yourself. Her ganks are incredibly strong though and her teamfight potential is insane. You can actually initiate with her and that's a godsend in a team where every is too much of a sissy to go in. E into the middle, root everyone in place and ult yourself or the enemy ADC. Your team can then proceed to wreck everyone while you'll activate your Zhonya's.