I saw this today and really enjoyed it. I saw it with my mom and DS's (young adults) and we all thought it was great. The younger ones didn't get the references to old Hollywood but that didn't seem to matter.
There are so many fab cameos and characters in it, and little strands of different stories, and I love films like that. All the actors are fantastic not just the ones you expect to be (Clooney, Brolin, Swinton, Johansson, Fiennes) but also the unknown ones like the cowboy and the starlet he goes on the date with.
For some reason I am always surprised how good Channing Tatum is in everything, even though I've never seen him be bad in anything! I think it's because he's such a pretty face, my brain won't accept he can be talented, funny, a great dancer etc as well!
On the way home me and my mom enjoyed working out the real-life references and who the characters were inspired by; Scarlet Johanssen was Esther Williams but her adopted baby story was Loretta Young, Channing Tatum was Gene Kelly, the starlet was Carmen Miranda, the cowboy was Roy Rogers, Tilda Swinton was Heda Hopper...I didn't get who George Clooney was but apparently he was any combination of Gary Cooper, Robert Taylor (who?), Charlton Heston, Marlon Brando, Kirk Douglas and Richard Burton. Funny because if I was going to cast Clooney as anyone from old Hollywood it would be Cary Grant!
I didn't realise Eddie Mannix was a real person! Apparently he was rumoured to have murdered the original Superman George Reeves (ruled a suicide) for having an affair with his wife.