I saw The Water Horse last week. It was cute and better than I expected it to be.
The Weta -created CGI looked really good of course. There wasn't as much dorky family-film comedy as the trailers lead you to believe. A solid 8/10 overall.
Now, anybody who knows anything about the real history of Loch Ness and the monster is going to be able to find a few screw-ups in the story. I'll put them in spoiler bars so as not to ruin the movie for anyone, but if you're a Loch Ness monster fan you might find these interesting:
1. [blackout]The movie takes place during World War II and it involves the creation of the famous "Surgeon's Photograph" hoax photo of Nessie. However, the Surgeon's Photo was taken in 1934, not during WWII. Modern day "monster" sightings started in 1933 after a new road was built around the shore of the Loch, well before WWII.[/blackout]
2. [blackout]In several scenes young Angus is riding on the monster's back as the monster dives deep beneath the Loch and Angus looks around underwater at the beautiful scenery. Overlooking how long Angus must be able to hold his breath during this sequence, the fact is that Loch Ness is full of black peat moss from the surrounding countryside. The water is so black that once you're more than 3 feet down you can't see anything at all.[/blackout]
3. [blackout]In the movie Loch Ness is actually right up against the ocean! In real life, Loch Ness is a freshwater lake and is connected to the ocean by the 12 kilometer-long River Ness. The River Ness is pretty wide, but very shallow in places, and nothing the size of a dinosaur could swim all the way through to the ocean.[/blackout]
But of course this movie is a fantasy, so it's best to just go with it and enjoy it as such.