We took ds to see it 3 wks ago, he loved it & it was his first ever trip to the cinema. He is 3 yrs, 7mths and got a bit scared by the biker but sat on daddy's lap and was fine after that! he hadn't seen spongebob on telly at all but enjoyed it nevertheless.
Saw one of my fave episodes today, whilst DD was eating her tea. The one where they go camping and sing the 'C-A-M-P-F-I-R-E S-O-N-G', makes me pee myself everytime I hear/see Patrick trying to keep up with the singalong.
ds (almost 6) was VERY scared by bits of it - the bar full of nasties, the biker, and even more the cyclops diver - think he finds suspense, and seeing vulnerable people/animals in danger, very frightening. Managed to persuade him to stay through it (theory being that the happy ending blots out the scary bits) and he's now announced it was his favourite bit of the holiday so far. But if you've got a timid child do be warned.