I hadn't picked up a Harry Potter book until I bought the first four together in a paperback set, then I realised that there may be a reason for all the fuss!
They were descriptive, humourous in places and had a nice feel about them, so when the next came out I got it straightaway, then the same with the next one, and the next one.
chrysalis_stage, the earlier ones have a much younger feel to them, but that's appropriate, as Harry is young, and the first readers would have been quite young. But the books mature, and the plot weaves it's magic until you have to know what happens next. I would definitely recommend them them as an enjoyable read.