J.H.
Just went to a 4 yr old's party there. It was fine. I've been to a ton of b-day parties by now, and it was just another one. They did some activities in the gym, then to the Fun Factory.
You can also check out The Little Gym in Newtown Square. And for my youngest's 2nd B-day we did Makin' Music in Aston. I'd recommend them if most of the party is 2 yrs old or so. They are more interactive with something to do, where as Kehlers you are just running around after them in the Fun Factory most of the time. That's fine if they are older and can do it on their own, but I get bored just helping them climb on things.
Have fun!