For all those interested, I highly recommend buying the British editions as they retain the writing style from Rowling. The US (Scholastic) versions have a lot of "Americanizations" of British words.
Personally I will admit to getting into HP late (just 2 months ago) but I bought the 5 book Special Edition set from Amazon.co.uk which is clothbound with embossed gold lettering and the paper and print quality is fabolous. They use a more adult font (Berkeley) than Scholastic, and the book looks more like a "real" novel (includes gilded paper edges and built in bookmark for each book). In the 2 months, I've finished all 5 books and have my regular British edition on order for Book 6 (the Special Editions come out about 4 months after the original release, so my Book 6 SE will be purchased in October).
I actually was never a fan of Mary Grandpre's artwork so the UK (and Canada/Raincoast) editions spare me from it. I like the person who does the cover art for the UK edition, and I don't miss the chapter artwork from Mary so I'm all set.
For those interested in textual changes from UK to US editions, I highly recommend
www.hp-lexicon.org - click on each book cover and it will take you to a page devoted to that book, and each has a link with textual changes from UK to US version. Be forewarned, it's an addicting site!