Here are two of my sites I built from Yahoo sitebuilder. They're good for an informational website. Don't know if I would recommend it for anything else.
PS: Sorry in advance, I haven't updated these sites for a little while due to a new baby, getting back to work, the holidays, and updating our shop's "ordering" site.
I am currently re-building my website with sitebuilder. I have an ecommerce site and will let everyone know how it works. There is some things I need to work out but so far I am pleased with the site. I am about a week from it being fully functional but I am learning a lot that I will be happy to pass on to anyone having questions.