Some people who have read the book hate both this TV series and the 1978 film. I've read the book, and do not hate them. Maybe because I saw the TV and film adaptations before.
This series is children's version of the classic novel - so unlike the 1978 film - there is considerably less violence and darkness. Most children will love it because of the endearing characters and fluent animation (quite good for a TV cartoon.) This was one of my favourite shows when I was little, and I liked it because of the way rabbits were presented - intelligent dignified and handsome creatures, not cutesy little balls of fluff.
I must confess, I saw the film before I saw this, and I like both. However, if it were not for this TV show, I would probably never have been eager to read, and love, the book. Many people do not like the 'kiddified' feel, but they do not realise the fact that this was created to introduce children of all ages to the amazing world of Watership Down.