To answer the parental question: I would probably be okay with taking an 8 year old (see below), but definitely wouldn't take an 8 year old to an IMAX showing because of the decibel levels. If I did, I'd definitely skip the trailers; I dunno about any other theaters, but the Captain Phillips one is insanely loud, like jet engine loud. I went to a Rancid concert a few weeks ago and stood in front a speaker for three hours--that trailer is at least 20% louder than that.
As for content, there's a
It's also really intense throughout, but age 8 is a good time to not be a weenie.
At 90 minutes, it's about 88 minutes of just perfection in about everything: cinematography, VFX, acting, and I didn't mind that script wasn't super-subtle about what it was about, until:
And don't get me wrong, I enjoyed the melodrama in general--just not that part.
I'm also not getting the Cast Away comparison everybody is making, other than the really general similarities (sure, they're in the same genre). Cast Away involves isolation and threat of death, sure, but it lasts for like three years. Further, Tom Hanks had a life, which was destroyed a little more every day he was on that island, and when he did finally return, he returned to nothing, and probably with serious trauma-induced mental illness. He was finished as the man he had been.
By contrast, Ryan Stone is in peril for about four and a half hours, and doesn't have anything to live for in the first place, but struggles anyway--that's the point of Gravity. They're practically opposite stories.