I've been to Six Penn a couple of times for lunch and dinner now. It's a nice spot, but not the top of the list. If you are looking for some "home" cooking it's a good choice.
The food isn't anything to brag about and it isn't too inexpensive, but I wouldn't count it out. The rooftop bar is nice, private and more of an outdoor lounge. It is actually comfortable to sit rather than most outdoor places in the city they just use metal patio chairs.