People can get themselves worked up about all kinds of things.... my college age niece has an irrational fear of koala's.... she's never seen a real koala to have had a negative experience, but if you show her a stuffed koala she'll flip out.
As to Dinosaur.. have seen plenty of the more easily scared types scream up a storm on it. But when my son was 8 he liked it, and we had a rainy evening with low crowd that we rode it like 5 times in a row doing different poses at the picture spot...was a good memory.
As others have mentioned, it is a bumpy ride that can aggravate any issues you may have.