I read the issue yesterday. Not bad.
I do agree that superheroes showing up at the school is stupid. BUT! The way it was done with Johnny was no big deal, I think. The way Iceman was brought in- that's the problem. Just ice-sliding in and all that...not needed. If he had shown up like Johnny, not powered up and what not, just 'casual', it would've been a lot better.
The only other problem is Liz. Well, her just becoming Firestar. I personally think that the real problem with Liz becoming Firestar is that she just becomes Firestar. There's no real build-up to this. It's just "I don't feel so good. Woof," and then later again, "I don't feel so good. Woof. Oops, I'm now on fire and okay."