I re-read Year 1 after I finished DH because I had the great luck of being able to introduce a 9 year old to Harry Potter. The writing style is dramatically different, so much more simplistic and much more like a typical children's book. It was wonderful to read it again. I loved it just as much as the first, second, third, ... many other times.

In JKR's interviews she indicated that she had written the last chapter of Year 7 at that same time as the first book. Of course! JKR's writing style evolved so much throughout the series that comparing 1 & 7 is really like you're reading an entirely different writer. I think because JKR had this idea in her mind about the ending all along that she missed this. She was too involved and to her it made perfect sense -- she'd been imagining it throughout the entire process. This is where the editors should have jumped in. They could have brought the two writing styles together.