I've loved The Eagle of the Ninth book since I was a child (though why exactly it is classed as a children's book I really do not know). And I loved the film too.
OK, it wasn't the plot from the book, exactly. No Cottia, and no Cub - well, that could have been worse. I was rather worried they might bump up Cottia's part and include her in the expedition North, which would have been a complete disaster : as it was, you can almost think that Cottia is just off-screen - though I'm not sure if Cottia would like the less sympathetic, indeed rather brutal and soldierly version of Marcus. That was a bit of a shock - Marcus in the book is such a likeable person - but I can see that to a viewer who is coming to the story fresh, Marcus is after all a member of a fairly brutal invading army and you need time to get through that. I think he could have been played a little less woodenly though.
There is a lot of violence and I was a little surprised that a film with that number of graphic beheadings in it - including executions of children - had a 12A certificate. I'm always baffled that sex seems to require so much more care for child watchers, than people chopping each other into chunks!
Esca was mostly spot-on and stole the show. Gotta love Esca. Though I think making Marcus less sympathetic, more Roman, as a character made Esca's motivations somewhat unclear - why is his loyalty to Marcus quite so absolute? In the book, Esca likes and respects Marcus well before he is put in any situation that actually tests that loyalty, whereas in the film, he seems to loathe him until after the decisive moment. OK, Marcus saved his life, but since Esca has by then repaid the favour several times over, why does he go on and help him steal the Eagle?
( I am sure there are lots of people who would answer that one with 'because he fancies the pants off him' - not that there is any obvious romance, but there's definitely a bit of a subtext - but frankly that is not an explanation: fancying the pants off someone might be a reason to trek dourly round the Highlands preventing people from slitting his throat and flinging him in a ditch, but I'm not sure it's an explanation for murder and Eagle-theft)
But I can live with that. And there were lots of deerhounds (? and some deerhound lurchers too I think.) More films should have sighthounds in...
The overall feel of early Roman Britain was great. I know some people have criticised the American accents for the Romans, but I'm not sure what accent I expect a Roman to have, so that actually worked quite well for me. Perhaps the pacing was not quite right for a film and that was why it missed the 'totally fabulous' quality that it could have had. That and the visuals are better inside my head. But it was pretty damn good.
Edited the next day : I'm not sure about the film ending. Not to give it away, but it is rather more up-beat than the book.
But, this morning I woke up with the tune I hear to 'the girl I kissed at Clusium' in my ears, and that wasn't even in the film! It made me happy.
Edited again, some days later
After I watched the film, I re-read the book. Then the story wouldn't go away for me, so I went back to the cinema and saw the film again, and picked up all sorts of tiny nice details I missed the first time. And actually, I think I was a bit unkind to the guy that plays Marcus : on a second viewing he doesn't look anything like as wooden and does a pretty good job of conveying Marcus's changing views of the world (though I still can't quite see the 'heartthrob' angle... )
How many films do you go to see and you walk out with the whole audience smiling and the teenage couple behind you are deep in a discussion of historical slavery, and the people are all talking about what actually happened to the Ninth Legion, apart from the elderly lady in front who is showing us all her best Roman shortsword moves? OK, film critics and people who don't care about history may not think much of this film, but who cares about them!