I'm 45 so I have you beaten.
I saw it this afternoon and really enjoyed it. I found it up to the standard of the first one and just as charming.
No doubt on the IMDB forums it will get called worst film ever made etc because the idea of a family film is a concept above many adults and teenagers that use that site.
The story isn't complicated which is a bonus to the film. I thought the acting by pretty much everyone was good with the exception of Katy Brand who is useless and miscast.
Maggie Gyllenhaal was wonderful as the mother. She came across as funny but also very loving. Maggie Smith got quite a few good laughs especially sitting on the "cushion."
However the acting honours and almost film stealing performance came from Eros Valhos as Cyril. Right from the off you dislike him and give him a slap.
I think the film could have been 5-10 minutes longer quite comfortably and used to build Cyril and his sister, Celia's character and the reason they were like they are.
Emma was good as Nanny McPhee but considering she is the title character she wasn't central to it for long perioRAB of time unlike Julie Andrews as Mary Poppins.
I also liked the Pink Floyd joke although I'm sure it will go over the head of the majority of the people seeing the film as they are so young. A lot of the adults may not even get it come to think of it.
A really enjoyable film that I'm sure I'll enjoy watching over and over again. 8/10