I'll never understand the allure of the Holga, but that's my problem. Very well done. The kids have neat 'attitudes'; I'll bet they're little charmers too. (BTW, Centering the subject in a square format is perfectly acceptable IMHO.)
I have to agree with Jovo re: centering. I'll take it a step further and say that the belief that decentering the subject is preferable has become more of an annoying rule than a naturally centered subject ever was. Just my opinion...