But that's the whole point, Alia! You're not supposed to like Artemis - he's one of the first true anti-heroes of children's fiction in years. I thoroughly enjoyed Artemis Fowl. I wasn't quite so keen on the second, but thought the third was very clever. Artemis had actually got too likeable by the end of book 3, so Eoin Colfer very cleverly re-invented him as a heartless villain.
I would not go as far as to say that Artemis is better than HP, but he's very different. I enjoyed both sets of books for different reasons, but enjoy them, I did.
Edit: I forgot to say that I've not yet read the latest volume - The Opal Deception. Is it any good?