I've upped my rating from 2.5 because my son loved it when I read it to him 

I did love the descriptions of nature and the scenes were all set brilliantly. I found Colin and, to a lesser extent Mary, tiresome and Colin's story became very repetitive and drawn out. I would have loved more about Dickon and Mrs Sowerby but they were thinly drawn.  There was also unquestioned colonialism and racism particularly at the start which was horrible. 

I think perhaps Colin's grandiosity was meant to be written for laughs but it didn't work for me.