I don't know what the significance of the 300th performance might be, but I'm not surprised it's run that long, and won't be surprised to see it reach 500 or more. Disney has deep pockets.
It's certainly not the worst show ever, it's just boring and not particularly well-crafted. The night I saw it the audience loved it, standing ovation, the whole over-the-top thing. That's what's so scary about it - the complete inability to be discerning. I have several friends involved in the production - almost from the first rehearsal it has not been a happy experience. It's a paycheck job.
Cheyenne Jackson tickled me. AFTER ordering SoMMS a drink but NOT tickling him, and hanging out with Girly in his dressing room (where he DIDN'T tickle her) but BEFORE we got married. To others. And then he tweeted Boobs. He also tweeted he's good friends with some chick on "The Voice" who just happens to be good friends with Tink's ex. And I'm still married. Oh, and this just in: "Pettiness, spite, malice ....Such ugly emotions... So sad." - After Eight, talking about MEEEEEEEE!!! I'm so honored! :-)