I got this and the second set when I was young, about 10ish, I think. :) I just re-read them recently, so I thought I'd give my thoughts.
I loved them, I really did. Vol. 1 was my favorite, mostly because I loved Merry and her Amish neighbors (especially the cute one, Levi) and the adventures they had. I loved the alliteration aspect. At that age I became obsessed with it too. I was pretty bad at it however... I'm glad it wore off.
However, as I get older I'm liking it less. You know though, it's a really cute book, and these first four are my favorites of the series.